Write
How to use sources?
Be consistent
Make sure that your references are consistent and uniform. Choose one referencing style and apply it in your text in great detail and while doing so, pay attention and be meticulous.
When to refer to sources?
Every sentence in which you write something that you have read somewhere, needs a reference to the source. You can refer to a source which is relevant for several sentences of your text but make sure the reference is clear. Your reader shouldn’t guess which part of your text comes from which source.
In Belgium, at least 200 microspecies of Taraxacum officinale have been described, although many sources no longer distinguish between them because of the numerous crossings between the microspecies (Karl,1980; Linné, 2001).
In Belgium, at least 200 microspecies of Taraxacum officinale have been described (Karl, 1980), although many sources no longer distinguish between them because of the numerous crossings between the microspecies (Linné, 2001).
You don’t refer to a source if you deduce or conclude. Every sentence that has no reference to sources represents your own ideas. It is, therefore, important to give enough arguments to support your claims.
Avoid quotes and paraphrase
It is your text, which means that your paper should mainly consist of your own words. Many students make the mistake of using too many quotes from other articles. It’s a much better idea to report what is said in your own words. This way, you show that you haven’t only read the sources but also that you have understood and interpreted them. Moreover, quotes interrupt the reading flow.
Try to paraphrase as much as possible. What is paraphrasing? Paraphrasing means that you formulate the message of a specific claim or article in your own words. If parts of the sentence are literally copied from the original, you still need quotation marks. A translation of the original doesn’t count as a paraphrase.
Hogewoning et al. (2012) wrote: “We show quantitatively that leaves acclimate their photosystem composition to their growth light spectrum and how this changes the wavelength dependence of the photosystem excitation balance and quantum yield for CO2 fixation. This also proves that combining different wavelengths can enhance quantum yields substantially.”. Souterrain (2015) studied this effect further: “The co-irradiation with blue and red light enhances the quantum yield for CO2 fixation in the leaves of several varieties of Camelina sativa.”
Firstly, Hogewoning et al. (2012) demonstrated that the composition of the photosystems in leaves is wavelength dependant, Souterrain (2015) developed different varieties of Camelina sativa with a high quantum efficiency of the CO2-fixation by co-irradiation with blue and red light.
You only quote if the claim is really short and strongly worded, which is rare. Don’t exaggerate with quotes. Don’t always quote a source if you are looking for a definition. Try to define the concept in your own words first. Besides, for quotations longer than 40 words, you must use a white space and an indentation.
Cite the primary source
If possible, refer to the source where a finding was published for the first time. Information in a source often originates from another source in turn. This frequently occurs in introductions of research papers, books and review papers. In this case, we call the original source the primary source and the source where it is cited the secondary source. If you can find and consult the primary source, you should use it and cite this as your own source. This has two reasons: 1) if a sentence is paraphrased multiple times, the meaning could be twisted until the original meaning is lost and 2) the original author gets credit for their work. Unfortunately, it is sometimes impossible to find the primary source. In this case, the reference list should clearly state that you used a secondary source. How you should clarify this, depends on the reference style you chose and can be found in the guidelines for this style.
The specific heat capacity of this substance is 564 kJ/kg/K (Yeo, 2022).
The specific heat capacity of this substance is 564 kJ/kg/K (D’Hael, 1985, as cited in Yeo, 2022).
How to refer to sources?
The most important referencing styles for bioengineers are the APA and the IEEE style. They look like this:
| APA | IEEE | |
|---|---|---|
| In-text references | There are four fundamental conditions for the formation of loess: a dust source, sufficient wind, a suitable accumulation area and sufficient time (Pye, 1995). | There are four fundamental conditions for the formation of loess: a dust source, sufficient wind, a suitable accumulation area and sufficient time [1]. |
| Reference list | Pye, K. (1995). The nature, origin and accumulation of loess. Quaternary Science Reviews, 14, nr. 7–8, pp. 653–667. | [1] K. Pye, “The nature, origin and accumulation of loess”, Quaternary Science Reviews, vol. 14, nr. 7–8, pp. 653–667, jan. 1995. |
Ask your supervisor which style to use. In any case, below you can read how these styles are used for the most frequently used source types. Are you still in doubt or did you come across a source that is not frequently used, look online. Both on the APA style and the IEEE style, lengthy overviews have been written. Regardless of the specific style you use, there are several things to keep in mind.
Don’t procrastinate
Try not to leave working on your reference list to the last minute. Keep track of what you have read in which source and immediately add that source to your reference list correctly (and consistent with all other references) when you use it in your paper. This will save you a lot of time later on.
Automate and check
Use specialised software such as EndNote, Mendeley and Zotero to avoid small mistakes and to make the work lighter. Besides, many of these packages can import and export BibTex-files.
Even if you use specialised software, you must always check your entire reference list.
Keep it clean and consistent
Your reference list should not only be complete but also consistent and clean. Stick to one referencing style and make sure you keep an overview. Is it difficult to find how to refer to a specific type of source? In that case, make a clear choice for yourself on the basis of the information that you found and stick to that style.
Unnecessary references
Every reference in your text refers to a source in the reference list and vice versa. Make sure you don’t include sources you don’t refer to. Such sources should be included in a separate reference list.
APA-style
The APA-style or the author-year-system is the most applied scientific reference style. This style determines not only how to refer to a source in your text but also how to refer to a course in your reference list at the end of your work.
Below you will find the most important principles of the APA-style and some examples that will help you use this style correctly. These tips are loosely based on Pollefliet, L. (2011). Schrijven: van verslag tot eindwerk: do’s & don’ts. Gent: Academia Press.
In-text references
If you use the APA-style, you refer to a source by adding “(author, year)” after a sentence or paragraph. If the author is unknown, you can also use “(abbreviated title, year)”. In any case, the combination you choose should match a source in the reference list.
If you would like to use the reference in a sentence, you can use “ author (year)” or “abbreviated title (year)” as an alternative. What that will exactly look like depends on the number of authors you are referring to.
If a source has one or two authors, you mention them all in your text:
Geeraerts (1997) argues that the scientific evolution of fertilizer production happened gradually throughout the 19th century.
The scientific evolution of fertilizer production happened gradually throughout the 19th century (Geeraerts, 1997).
Shen and Su (2011) have observed that mercury pollution is the most important factor in the development process.
The most important factor of this development process is mercury pollution (Shen and Su, 2011).
If a source has three or more authors, you only mention the first author, followed by “et al.”. In the reference list, you mentioned all authors of course.
Trewani et al. (2018) warn for the negative consequences of radiation on the biorhythm of micro-organisms.
This radiation is presumably harmful for the biorhythm or micro-organisms (Trewani et al., 2018).
Multiple sources that support the same claim, should be put next to each other with a semicolon in between:
King (2001) describes how these processes can influence the fertility of the earth surface (see also Berghe et al., 2017; March, 2012).
These processes influence the fertility of the earth surface (Berghe et al., 2017; King, 2001; March, 2012).
If you refer to multiple articles from the same author (or an author with the same name) from the same year, you add letters after the year:
In his most successful year, Einstein conducted research into the photoelectric effect, the Brownian motion and the special relativity theory (Einstein 1905a, 1905b, 1905c).
In collective works, the name of the author is used and not the name of the editor. In other words, you are looking for the name of the writer of the chapter or article and not the name of the composer.
Some sources don’t mention authors. If you can consider an institutions as the author, you can use that in your reference:
Government data have shown that the proliferation of ecolabels leads to confusion among consumers (Federal Public Service Economy, 2016).
If you can’t find a person nor an institution that you can use as author, you should use the title of the source or an abbreviated version of it. Although you have a lot of freedom in this case, we advise you to make logical and consistent choices as much as possible. For example, use the first noun in the title or use the title without articles, ordinal numbers, etc.
Title of the source: The second national report of the average consumer’s perception of ecolabels.
In-text reference: (Report, 2016)
This approach should also be used for norms, law articles and other types of documents with no clear authors. To refer to a norm, for example, you can use its specifications and year:
All rules above can also be applied to digital sources. If the author of a website is known, you mention it. If the author is unknown, you use a version of the title:
UGent (2020) declares in an online press release that the Wikipedia article on its history contains blatant errors (History of Ghent University, 2020).
If the year of the source is missing, write “n.d.” (no date) or “s.d.” (sine dato), but always be consistent:
The experiments conducted by Beketov (s.d.) form the starting point aluminothermy.
You will usually adjust tables and figures that you take over from other sources to the style of your own work. Therefore, you use the phrase “adaptation from the author (year)”.
Order of the reference list
Your reference list is ordered alphabetically on the basis of the names of the authors and the abbreviated titles. If an author or title is cited multiple times because they belong to multiple works, you order them chronologically from old to new. If you have consulted articles from a specific author who sometimes publishes alone and sometimes together with colleagues, you mention the individual articles first and then the others.
In the past decennia several new insights have arised on the relation between roasting cacao beans and the quality of chocolate. Zweefham (1996) has shown that roasting at low temperatures leads to a relatively complex and aromatic flavour. This is implicitly confirmed by Aardnoot (2001), who has found an intense but bitter and less complexe taste in chocolate roasted at high temperatures.
References
Aardnoot, Z. (2001). High roasting of cacao beens. Flavor magazine, 6, pp. 200-205.
Zweefham, A. (1996). Low roasting of cacao beens. Cacao research, 5, pp. 100-105.
Books and seperate publications
Following the APA-style, a book or other separate publications should be referred to in a reference list as follows:
Authors. (year). Title and subtitle. Place of publication: name publisher.
Vidhyasekaran, L. (2016). Switching on Plant Innate Immunity Systems: Bioengineering and Molecular Manipulation of PAMP-PIMP-PRR Signaling Complex. London: Springer International Publishing.
The authors should be mentioned in the same order as is the case in the work itself and their names should be abbreviated as follows:
Kwak, A.J., Mouse, M. and Einstein, A.
Be careful: don’t use a blank between the initials of an author and leave out all titles (prof., dr., ir.). The title and the subtitle of the book should be put in italics.
Collective works, for which editors composed the work of different authors, are referred to in the same way:
Editors. (Eds.) (year). Title and subtitle. Place of publication: name publisher.
Yarmush, M.L. and Golberg, A. (Eds.) (2017). Bioengineering in Wound Healing: A Systems Approach. Singapore: World Scientific Publishing.
For editors, the same rules apply as is the case for authors.
If the year is missing, you can write (n.y.) (no year) or (s.d.) (sine dato). However, it’s better to mention why you can’t find the date and write something along the lines of (in print) or (in preparation).
A closed or half open interval can be included as (year) (2001-2011) or (2008-). This doesn’t mean that you are uncertain about the exact date but that the work is composed on the basis of parts that were published in different years.
If you know the print of the work, you add it after the year:
Authors. (year, print). Title and subtitle. Place of publication: name publisher.
Maiti, P.D. and Maiti, P. (2017, 2nd print). Biodiversity: Perception, Peril and Preservation. Delhi: PHI Learning Private Limited.
Sometimes it is useful to mention the type of publication (syllabus, master’s thesis, etc.). You don’t need to put this in italics but rather you square brackets after the title and the subtitle:
Authors. (year, print). Title and subtitle [type of publication]. Place of publication: name publisher.
Frodeman, R., Klein, J.T. and Pacheco, R.C.S. (2017, 2nd print). The Oxford Handbook of Interdisciplinarity [handbook]. Oxford: Oxford University Press.
If the place of publication is missing, you can write (n.pl.) (no place) or (s.l.) (sine loco). If the authors, editors or translators have published the work themselves, you write “published in-house” instead of the name of the publisher.
Articles from journals or books
Scientific articles are usually not published separately but in a journal or a book.
An article from a journal should be included like this in a reference list:
Authors. (year). Name article. Title journal, number, pp. pages.
Erdman, P. (2019). Systems of Ecological Thinking: A Literature Review. Journal of Ecology, 5, pp. 459-474.
If the journal is published monthly or daily, you should write (year, month) or (year, day, month) respectively instead of (year). The page numbers of the article should be mentioned after “pp.”.
When it comes to the number of the journal, things start to get a bit tricky. Some journals are numbered per year which means that the page numbers are reset once a year. Other journals start every volume or number with page 1. If a journal is numbered per year, you only need to include the year (in italics):
Authors. (year). Name article. Title journal, year, pp. pages.
Chen, S. en Su, X. (2018). Glow in the Dark: Fluorescent Components in Scyliorhinus Retifer Skin. Biodiversity, 45, pp. 590-596.
If a journal is numbered per volume or number, you should also include the volume (italicized) and number (not italicized):
Authors. (year). Name article. Title journal, volume, nr. number pp. pages.
Hoeste, N. en Honengaerts, C. (2020). Communicating Biosources: A Systems Approach. Biocommunication Journal, 13, nr. 3, pp. 133-139.
Note that you don’t need to mention the place of publication and the publisher in case of an article from a journal.
This should be done, however, in the case of an article from a book. Moreover, you should also mention the editors and write “In” before the book’s details:
Authors. (year). Name article/chapter. In Editors (Eds.), Title and subtitle book , pp. pages. Place of publication: name publisher.
Bep. A. en De Kok, B. (2016). New Digitalism in Genetics: Criticism and Ethics. In A. Koeman en F. Ballerini (Red.), A New Era for Genetics: Trends and Innovations, pp. 76-110. New York: Springer Nature Publishing.
All other rules for books and separate publications also apply to articles from journals and books.
Digital sources
If you consult a version of a source that is only available online, you mention “Consulted on data via URL” at the end of your reference.
For e-books, you simply follow the APA-style for physical books:
Authors. (year). Title and subtitle. Place of publication: name of publisher. Consulted on data via URL.
Ravelli. P. (2020). The Future of Agriculture: Research and Innovation. Cambridge: Cambridge University Publishing. Geraadpleegd op 23/06/2020 op https://thefutureofagriculture.ravelli.com.
Most of the articles you will use are merely online versions of physically published articles. Even though you consulted them online, you should refer to them as physical articles from journals.
If you did use a journal article that is only published online or an online article that differs from a physical version, you refer to it like this:
Authors. (year). Name article. Title journal, number, pp. pages. Consulted on date via URL.
Roncfort, G. en Bardet, J. (2019). Mice Plagues in Venice: Causes and Consequences. Journal for European Health Research and Society, 43. Geraadpleegd op 09/03/2020 via https://jehras.com/4334.Roncfort-Bardet.
A website can be referred to in many different ways. If you know the authors and the title of the page, you write this:
Authors. (year). Title page. Consulted on data via URL.
If you only know the title, you have some more freedom. If the title is short, you can mention it at the beginning. If the title is quite long, you use the abbreviated version at the beginning:
Title page. (year). Consulted on date via URL. Abbreviated title page. (year). Full title page. Consulted on date via URL.
In all these cases, you can also add the title of the website after the (full) title of the page:
Abbreviated title page. (year). Title website. Consulted on date via URL.
If you only know the authors, you can mention only them:
Authors. (year). Consulted on date via URL.
Also don’t forget to include the specialised software you used in your reference list. Often it’s easy to find the authors. You should write this:
Authors. (year). Title software [software]. Place of publication: name publisher.
If it is unclear who made the software, you refer to the title of the package:
Titel software [software]. (year) Place of publication: name publisher.
Other sources and craziness
Most sources you will use as a bioengineer can be categorised as book, article or digitale source. If that is not the case, you can always use the general rule:
Authors. Title document. (year). Title publication. Place of publication: name publisher.
A norm, for example, should be referred to like this:
NEN 1000. (2016). Regels voor het hanteren van het Internationale Stelsel van Eenheden. Delft: Nederlands Instituut voor Normalisatie.
A patent, for example, should be referred to like this:
Cameron B. and Crouzet J. (2006). European patent No. 0673422 B1. Munich, Germany. European Patent Office.
In this case, use the same rules as for books and articles. If the year is missing, for example, you write (n.y.) or (s.d.) instead of (year).
Don’t be too creative. Reference lists are not the place to experiment. If you really need that one crazy source, look online. Libraries were filled with texts on the topic of the APA-style: your source will not be that crazy.
IEEE-style
The IEEE-style is a referencing style that is applied in many of the engineering disciplines such as electronics, computer sciences and biomedical sciences. This style not only determines how to refer to a source in your text but also how to refer to a course in your reference list at the end of your work.
In-text references
In the IEEE-style, you refer to a source by adding square brackets with a citation number at the end of a sentence or paragraph. These citation numbers should of course correspond to a source in the reference list.
The scientific evolution of fertilizer production happened gradually throughout the 19th century [1].
If you would like to use the reference in a sentence, you can use “Author [1]” as an alternative. What that will exactly look like depends on the number of authors you are referring to. If a source has one or two authors, you mention them all in your text:
Geeraerts [1] argues that the scientific evolution of fertilizer production happened gradually throughout the 19th century.
Shen and Su [1] have observed that mercury pollution is the most important factor in the development process.
If a source has three or more authors, you only mention the first author, followed by “et al.”. In the reference list, you mentioned all authors of course.
Trewani et al. [1] warn for the negative consequences of radiation on the biorhythm of micro-organisms.
You will usually adjust tables and figures that you take over from other sources to the style of your own work. Therefore, you use the phrase “adaptation from the author [1]”.
Order of the reference list
Your reference list has the same order as the order in which the references appeared in your text.
In the past decennia several new insights have arisen on the relation between roasting cacao beans and the quality of chocolate. Zweefham [1] has shown that roasting at low temperatures leads to a relatively complex and aromatic flavour. This is implicitly confirmed by Aardnoot [2], who has found an intense but bitter and less complex taste in chocolate roasted at high temperatures.
References
[1] A. Zweefham, “Low roasting of cacao beans”, Cacao research, vol. 5, pp. 100-105, januari 1996.
[2] A. Aardnoot, “High roasting of cacao beans”, Flavor magazine, vol. 6, pp. 200-205, februari 2001.
Books and separate publications
Following the IEEE-style, a book or other separate publications should be referred to in a reference list as follows:
Authors, Title: subtitle. Place of publication: publisher, year.
[3] L. Vidhyasekaran, Switching on Plant Innate Immunity Systems: Bioengineering and Molecular Manipulation of PAMP-PIMP-PRR Signaling Complex. London: Springer International Publishing, 2016.
The title and the subtitle of the book should be put in italics.
The authors should be mentioned in the same order as is the case in the article.
The first names should be abbreviated, followed by a full stop. Before mentioning the last author, you write ‘and’. (A. J. Kwak, M. Mouse and A. Einstein). Be careful: don’t use a blank between the initials of an author and leave out all titles (prof., dr., ir.).
[13] A.J. Kwak, M. Mouse and A. Einstein, Pinda Fever: Research into Pinda Variants. Paris: Walt Publishing, 1996.
[34] W.K. Chen, Linear Networks and Systems. Belmont, CA: Wadsworth Press,
2003.
[3] R. Hayes, G. Pisano en S. Wheelwright, Operations, Strategy, and Technical Knowledge. Hoboken, NJ: Wiley, 2007.
[9] Council of Biology Editors, Scientific Style and Format: The CBE Manual for Authors, Editors, and Publishers, 6th ed., Chicago: Cambridge University Press, 2006.
Collective works, for which editors composed the work of different authors, are referred to in the same way:
Editors, eds. Title and subtitle. Place of publication: name publisher, year.
[7] L. Spudich and B. H. Satir, eds., Sensory Receptors and Signal Transduction. New York: Wiley-Liss, 2001.
If the year is missing, you can write (n.y.) (no year) or (s.d.) (sine dato). However, it’s better to mention why you can’t find the date and write something along the lines of “in print” or “in preparation”.
A closed or half open interval can be included as (year) (2001-2011) or (2008-). This doesn’t mean that you are uncertain about the exact date but that the work is composed on the basis of parts that were published in different years
If you know the print of the work, you add it after the subtitle:
Authors, Title: subtitle, print. Place of publication: publisher, year.
[21] B. Drucker, Reptiles and Agriculture. 2nd ed. New York: Springer, 2001.
Sometimes it is useful to mention the type of publication (syllabus, master’s thesis, etc.). Add this information at the end, not in italics but between square brackets:
Authors, Title: subtitle, print. Place of publication: publisher, year [Type of publication]
[21] B. Drucker, Reptiles and Agriculture. 2nd ed. New York: Springer, 2001. [Handbook]
If the place of publication is missing, you can write n.pl. (no place) or s.l. (sine loco). If the authors, editors or translators have published the work themselves, you write “published in-house” instead of the name of the publisher.
Articles from journals or books
Scientific articles are usually not published separately but in a journal or a book.
A scientific article should be included in a reference list like this according to the IEEE-style:
Authors, “Title of the article”, Name of the journal, vol. volume number, nr. issue number, pp. pagina numbers, month year.
[12] A. Nelson, R. J. Davis, D. R. Lutz and W. Smith, “Optical generation of tunable ultrasonic waves”, Journal of Applied Physics, vol. 53, nr. 2, pp. 1144-1149, February 2002
If the volume or issue number are missing, you can replace them by the date of the issue. Depending on the publishing frequency of the journal, you only mention the month or the day and the month. In both cases, it’s not necessary to also add the month at the end of your reference:
Authors, “Title of the article”, Name of the journal, Day Month, pp. pages, year.
[27] B. Metcalfe, “The numbers show how slowly the Internet runs today,” Infoworld, 30 September, pp. 34, 2006.
Note that you don’t need to mention the place of publication and the publisher in case of an article from a journal.
This should be done, however, in the case of an article from a book. Moreover, you should also mention the editors and write “In” before the book’s details. You can also choose to include only the page numbers of the chapter or the numbers of the chapter:
Authors, “Title of the article”, in Title: subtitle of the book, Place of publication: Publisher, year, ch. chapter, pp. pages.
[9] H. C. Hottel and R. Siegel, “Film condensation”, in Handbook of Heat Transfer, 2nd ed. New York: McGraw-Hill, 2011, h. 9, pp. 78-99.
If you refer to (part of) a collective work, you mention both the authors and the editors:
Authors, “Title of the article”, in Title and subtitle book, Editors (Eds.), Place of publication: Publisher, year, ch. chapter, pp. pages.
[10] W. M. Rohsenow, “Heat transmission”, in Thermal Radiation Properties, vol. 3. M. W. Catton and J. P. Hartnett, eds. New York: Macmillan, 2012, ch. 9, pp. 37-62.
All other rules for books and separate publications also apply to articles from journals and books.
Digital Sources
If you consult a version of a source that is only available online, you mention, after the year, the type of electronic source ([Online]. [E-book], etc.), followed by the source (“Available”). Moreover, always try to mention the last time you consulted the source (“[Consulted on date]”).
For e-books, you simply follow the IEEE-style for physical books:
[19] L. Bass, P. Clements and R. Kazman, Software Architecture in Practice, 2nd ed. Reading, MA: Addison Wesley, 2003. [E-book] Available: Safari e-book.
Most of the articles you will use are merely online versions of physically published articles. Even though you consulted them online, you should refer to them as physical articles from journals.
If you did use a journal article that is only published online or an online article that differs from a physical version, you refer to it like this:
[20] A. Altun, “Understanding hypertext in the context of reading on the web: Language learners’ experience”, Current Issues in Education, vol. 6, nr. 12, July 2005. [Online]. Available: http://cie.ed.asu.edu/volume6/number12/. [Consulted on 2 December 2007].
A website can be referred to in many different ways. If you know the authors and the title of the page, you write this:
Authors. “Title page”, Title website. [Online] Available: URL. [Consulted on date]
[2] J. Geralds, “Sega Ends Production of Dreamcast”, vnunet.com, sect. 2, 31 January 2007. [Online]. Available: http://nli.vnunet.com/news/1116995. [Consulted on 12 September 2007].
If you don’t know the authors, you can use the title only:
[2] “Sega Ends Production of Dreamcast”, vnunet.com, sect. 2, 31 January 2007. [Online]. Available: http://nli.vnunet.com/news/1116995. [Consulted on 12 September 2007].
Also don’t forget to include the specialised software you used in your reference list. Often it’s easy to find the authors. You should write this:
Authors. Title software. [Software] Place of publication: name publisher, year.
If it is unclear who made the software, you refer to the title of the package:
[3] Thomson ISI, Endnote 7. [CD-ROM]. Berkeley, CA: ISI ResearchSoft, 2006.
Other sources and craziness
Most sources you will use as a bioengineer can be categorised as book, article or digitale source. If you really need that one crazy source, look online. In this case, use the same rules as for books and articles. If the year is missing, for example, you write (n.y.) or (s.d.) instead of (year).
A norm, for example, should be referred to like this:
[1] IEEE Criteria for Class IE Electric Systems, IEEE Standard 308, 1969.
A patent, for example, should be referred to like this:
[5] J.P. Wilkinson, “Nonlinear resonant circuit devices,” U.S. Patent 3 624 125, July 16, 1990.