Citing sources

You must cite all sources and tools you used in your work, such as publications, textbooks, software, etc.

This also applies to translation tools or ChatGPT.

In principle, only sources that can be read and verified by others should be cited.

You can cite either verbatim (direct quotation) or paraphrased in your own words (indirect quotation).

In the Natural Sciences, it is common to paraphrase sources – in other words, to read the original text and summarize the relevant aspects in your own words.

For more than two authors, abbreviate with “et al.”, e.g. (Böhme et al. 2014).

When citing, you must also include the exact page number of the reference, e.g. [5, p. 854].

For multiple pages, indicate the range, e.g. [5, p. 852–856].

In direct quotations, the cited text is placed in quotation marks and reproduced exactly as in the original source:

• If words must be inserted for better understanding, enclose them in square brackets.
• If parts are omitted, indicate this with […]. This is only acceptable if the meaning remains unchanged.

It is important that each reference appears only once in the bibliography.

For textbooks or sources from which you cite different sections, also include the respective page number in the in-text reference.

In the bibliography at the end of your work, list all literature you used in full.

Basic subject knowledge is excluded from citation requirements, e.g. you do not need to specify where you obtained the molar mass data.

Avoiding plagiarism

If you do not identify direct or indirect quotations from the literature as such, this constitutes plagiarism.

Plagiarism may result in your work being graded as failed. If you are unsure, ask your supervisor.

Citation style and bibliography

Please note the information provided in the general Moodle course of the Faculty of AC for guidance on citation styles and suitable reference management programs.

Bibliography:

• The bibliography is a complete list of the sources you used, included at the end of your work. List only those sources you have cited in your text.
• The bibliography should allow readers to trace the sources you used. Entries must be detailed enough for readers to locate and consult the source themselves.
• The bibliography must be complete and consistent in format.
• References are ordered according to their appearance in the text. Each entry ends with a period.
• If you use a citation style other than the one recommended by the faculty, discuss it with your supervisor.
• Online sources must also be cited, always including the date of access.
• Abbreviations of chemistry journals can be found on the Chemical Abstracts Service (CAS) website.

Example: U. Böhme, S. Tesch, Citing: Why and How? Nachr. Chem. 2014, 62 (9), p. 852–857.

Frequently asked questions

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Regulations

When citing online sources, you should follow these two rules:

1. Understand the principle: Readers must be able to classify the source and find it themselves based on your reference.
2. Cite consistently: Stick to the chosen citation style throughout your work.

We recommend treating a website like a printed publication – that means providing the author(s), date, and title whenever possible, and using the web address instead of publisher and location.

Since online documents and websites can change, you should also include the date when you last accessed the website.

In the reference list, you list a website as follows:
Last name, First name (DD.MM.YYYY): Title. If applicable, publishing institution. URL (retrieved on DD.MM.YY).

Older recommendations for citing online sources sometimes suggest listing them separately.

We advise against this due to the increasing popularity of online sources.

Similarly, the note “Online on the internet” can be omitted – readers will recognize this from the web address.

Websites have some specific characteristics compared to printed publications that can cause difficulties:

• The information is often incomplete, e.g., publication date, author(s), or page numbers may be missing.
• Websites are unstable, i.e., they can easily be deleted, changed, or moved.

Incomplete information

Of course, you can only include what is given. However, if the information is incomplete, you should check whether this source really meets scientific standards. You might find a better source.

If you decide to cite the source anyway, use the available information to ensure traceability:

If the date is missing, use “n.d.” for “no date”.

If the online source is an unusual format – a blog post, a tweet, a YouTube video etc. – include the format in square brackets after the title.

Instability of web addresses

Here today, gone tomorrow – online sources can easily be moved or deleted. This characteristic of online sources conflicts with the requirement for scientific sources: ensuring traceability.

This does not mean that you must never cite from the internet, but you should consider the following tips:

• Check whether you can find an equivalent printed source.
• Choose online sources from reputable publishers, such as e.g., universities, academic journals, or ministries. This does not guarantee the source will still be online tomorrow, but it increases the probability.

If a date of last change or update is available, include it.

Discuss with your supervisor whether you should archive the cited websites, e.g., by printing or saving them on a data carrier that you include with your work.

Usually, however, this is not necessary.

Literature: APA Style (2010): How do you cite website material that has no author, no year, and no page numbers? http://www.apastyle.org/learn/faqs/cite-website-material.aspx (retrieved on 14.10.2021).

Literature: Bleuel, Jens (2001): Citing online sources. In: Hug, Theo (Ed.): How does science acquire knowledge? Volume 1: Introduction to academic work. Hohengehren: Schneider. http://www.bleuel.com/ip-zit.pdf (retrieved on 14.10.2021).

Frequently asked questions

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At the end of the paper you will find the bibliography. Here all (and only) used sources are listed. If you use a numerical citation style, the sources will be listed with their number in the order of their first appearance. If an author-year style is used, the sources are sorted alphanumerically.

The following gives the specifications of different types of literature according to the citation style IEEE Editorial Style Manual (German), which is often recommended for engineering papers. You can find the citation style in the reference management programs Zotero and BibTEX.

Note any differing citation guidelines from your instructors.

Monographs

In the academic context, a monograph is a book written by one or more persons, without specific parts being attributable to individual authors.

How it’s done: [No] Initial of first name. Last name, Title, Edition, Place(s) of publication: Publisher, Year.

If it is the first edition, the specification is omitted.

Collected volumes, encyclopedias and handbooks

Collected volumes are books whose chapters (contributions) come from different people. This usually also applies to encyclopedias or handbooks. For encyclopedias and handbooks, you should make sure they are subject-specific, not general reference works.

The editors, abbreviated as Eds. or Ed., publish the entire work.

How it’s done: [No] Initial(s) of first name. Last name (author), “Title of contribution” in: Title of collected volume, Initial of first name. Last name (editor), Ed., Edition, Place(s) of publication: Publisher, Year, p. (first page of contribution)–(last page of contribution).

Internet documents

Internet documents are unstable: they can be deleted, changed, and moved. Therefore, you must always state the date on which you last accessed the source. Also pay attention to reliable, authoritative sources.

Sources that exist both in print and online should be cited in their print version (e.g. the titles on Springer Link in the university intranet).

You can additionally provide the URL.

How it’s done: [No.] Initial of first name. Last name, Title of the Internet document, Year. [Online]. Available at: URL (Accessed: Date).

Attention: If you have automatic hyphenation activated in your word processing program, make sure that no hyphenation marks sneak into your URL entries. It is best never to break your links in the middle of a word, but after a special character.

Blogs, wikipedia and videos

Since modern developments are often published on the web first, it may happen, especially in the open-source and security fields, that no books, journals, or proceedings (conference volumes) exist on the given topic.

In this case, always search for and cite the original source of information, and under no circumstances rely on news aggregators or dubious blogs.

Blogs of well-known experts, on the other hand, can be worth citing – in exceptional cases also tutorials, e.g. for particularly complex topics.

Wikipedia is controversial among faculty. But you can use Wikipedia as a starting source to familiarize yourself and to find further references.

Note that there are good as well as poor Wikipedia articles.

Only use Wikipedia as a source if the online encyclopedia is truly the best source. Normally, however, you will always find original sources there.

When using internet documents, save the webpage with “Save as” including all graphics and embedded materials, and copy these onto the accompanying storage medium. In the bibliography, state the date on which you saved the page.

Videos, e.g. from YouTube, are generally not citable, since they usually cannot be downloaded for archiving, or it is not permitted.

Digital Object Identifier?

For digitally available books and journals, a Digital Object Identifier (DOI) is increasingly specified.

A DOI is a worldwide unique identifier assigned to a book or to a single article in a journal.

The identifier consists of a publisher code and an object code, separated by a slash. Behind the URL http://dx.doi.org is an international database that determines, for a DOI, the corresponding URL under which the work can be retrieved via HTTP.

The advantage of this indirect indexing is that the DOI always remains constant. If the object URL changes, the publisher only needs to update the reference address in the database (e.g., when the publisher changes, or the server architecture changes).

Journal articles

In journals, the individual issue is usually identified with a number. Several issues (typically three to eight) are combined into a volume.

Since in a volume the page numbering simply continues, this means that in a single issue of the volume the first page usually does not start with one, but the numbering continues from the previous issue (except when a new volume begins).

Journal titles that consist of more than one word (like Science or Nature) are abbreviated (e.g., Data Science and Engineering as: Data Sci. Eng.).

This is how it’s done: [No.] Initial of first name. Last name, “Title of the article”, Title of the journal, Volume, Issue number, pp. [first page of article]–[last page of article], Year.

Standards

DIN standards, VDI guidelines and VDE regulations must also be cited.

This is how it’s done: [No.] Title of the standard – Subtitle, Number, Date.

Patent

How it’s done: [No.] Author, “Title of the patent,” Patent number, Date.

By the way: You can include extensive information on patents in the appendix.

Academic theses

Academic theses include bachelor’s theses, master’s theses, and dissertations.

Dissertations are always citable if they have been published.

Citing other academic theses can be appropriate in individual cases: If you want to cite an unpublished bachelor’s thesis or master’s thesis, you should discuss this with your instructors. It is permissible if the cited thesis contains relevant research findings.

How it’s done: [No.] Initial of first name. Last name, “Title”, Type of thesis, University, Year.

Image sources

Oral information

Oral information that you receive e.g. from colleagues is cited in a footnote as follows: “¹Personal communication from Ms. G. Samplecolleague”. In the case of multiple mentions, this source can also be listed on the bibliography. However, it is only in rare cases a valid source.

Discuss this possibility with your professors.

Works with multiple authors

Even for works with two or more authors, according to IEEE, all contributors are listed on the bibliography.

The Latin addition “et al.”, meaning “and others,” is only used when not all contributing persons are known.

Tips for your bibliography

1. Create the bibliography automatically with the help of a reference management program such as Citavi or BibTEX (for LATEX).
2. Make sure that all entries in the bibliography are consistent and correct.
3. For contributions in edited volumes, always provide both the title of the contribution with the authors and the title of the complete work with the editors. State the full page range of the contribution. Only then can it be traced exactly which contribution or article you are citing.
4. Entries on the bibliography end with a full stop.
5. Publisher names are listed without the legal form of the publisher (e.g. GmbH, OHG) or the word “Publisher.” Exception: If the word “Publisher” is part of the publisher’s name, as for example with PRH Publishers Services.
6. Keep the order of authors as given in the source. The order was chosen deliberately.
7. Academic titles (such as Dr. or Prof.) are not included in the bibliography.
8. Lecture scripts usually do not count as scientific publications, since they are not generally accessible, and therefore are not citable.

OWL quiz: test yourself

And now it’s your turn! Find 10 errors that we have hidden in the following bibliography. Click on the spots where you suspect an error. A green checkmark shows that you are correct. A red cross means there is no error there.

The bibliography is a mandatory part of the structure of a scientific paper.

Frequently asked questions

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Basics

The examples are to be understood as suggestions. Depending on the faculty and professors,  formal requirements may vary.

Develop your own transparent, consistent and comprehensible system for referring to conducted interviews. Explain your chosen system in your thesis, e.g. in the methodology section or at the beginning of the results. How exactly you indicate interview excerpts depends on the purpose and, if applicable, your professors’ requirements.

It must be clear who the interviewee is, which interview it comes from, and where the quote is located (line, segment, paragraph, page etc.).

Quotes can be given directly or indirectly.

In the following example, the source is indicated line by line. In the interview transcripts you must display the line numbers for this:

Interview XY, L. 114–118

The following format is suitable when using MAXQDA or other software for qualitative data analysis:

BT, Int 3, Segment 4

BT, I3–4

BT here stands for the anonymised interview partner. It is the third interview, and in that interview the 4th segment, which can be located via MAXQDA.

If less precision is sufficient, you can also indicate the page number of the transcribed interview. You should explain how to read the short reference in the methodology section:

Example: The results are illustrated with references to the data. For example, the form I1–4 is used, where I1 stands for “Interview 1” and the following number indicates the paragraph number in the respective interview.

Direct quoting

Here is an example of how to quote directly from your data:

Indirect quoting

The following are several possible ways of quoting indirectly from your data. Other formats are also possible – the main thing is that readers understand what your references mean.

The abbreviations JA, GK and PE refer to different interviewees. You must explain this elsewhere in the thesis, e.g. in the methodology section or the first time each abbreviation appears. The results are illustrated with references to the data. For example, the form I1–4 is used, where I1 stands for “Interview 1” and the following number indicates the paragraph number in the respective interview.

Providing information in the appendix

You do not list the interviews you conducted yourself in the bibliography.

In the appendix, you could optionally include the full transcripts of the interviews if necessary. Clarify this with your professors.

Frequently asked questions

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