Writing various types of scientific papers requires attention at all stages: from planning and conducting the research to formatting the references. It is worth noting that it is with the latter aspect that many authors have problems that subsequently lead to mistakes. And here a logical question arises: how to minimise risks and what to look for when referencing a research paper? Today, we are going to discuss the main citation styles and the rules to follow.
Citation styles: what are they for?
References – are an integral component of all these types of academic papers: a term paper, a diploma thesis, a monograph, and a dissertation. There are a number of requirements for the formatting of this section, as it contains the sources to which the author refers in the text.
A well-designed bibliography not only confirms the author's scientific integrity but also provides an opportunity to verify the accuracy of the data provided. In addition, strict adherence to the requirements for creating a list of references helps to avoid plagiarism and facilitates easier orientation in scientific works, both for the author and for other researchers who refer to his or her work.
There are dozens of different citation styles used in different countries. However, among them, there are several formats that are considered international and are actively used by researchers when writing scientific papers. In this article, we will look at the four main styles that are most commonly used to create a bibliography and cite sources in research papers.
1. APA (American Psychological Association)
APA – is the most commonly used referencing style in the scientific community. It was developed by the American Psychological Association and is mostly used in the fields of psychology, sociology, anthropology, education, and other humanities and social sciences. However, its use is widespread beyond these disciplines, as it is a convenient and structured tool for properly referencing sources.
In general, there are seven editions of the APA citation style, and the most widely used is the sixth edition, which is called APA 6th referencing style.
APA style examples of formatting:
An example of how to cite a source in a text:
- Single author: According to J.D. Brown (2025)...
- Two authors: According to A.B. Johnson and C.D. Williams (2025)...
- More than two authors: According to R.T. Harris et al. (2025) was developed...
An example of how to cite a source in a text:
- One author: (Brown, 2025).
- Two authors: (Johnson & Williams, 2025).
- More than two authors: (Harris et al., 2025).
- If the source does not have an author: (Nature Communications..., 2025)
- If the date of publication is not specified: (Nature Communications..., n.d.)
It should also be noted that if you use a reference to a source in the text, it is recommended to put it at the end of the sentence.
2. CSE (Council of Science Editors)
The CSE (Council of Science Editors) citation style – is one of the most common formats that is widely used in scientific publications, especially in the natural and applied sciences. It includes various citation options, depending on the type of source and the requirements of a particular publication.
It is worth noting that there are three CSE in-text citation systems, namely: citation-sequence, title-year, and citation-title. Below, we will discuss each of them in more detail.
- Citation-sequence: references in the text are numbered according to their first appearance, and each number assigned to a source remains constant for all subsequent references to that source in the text. In other words, in the final list of references, sources are arranged in the order of their first citation, i.e. each reference is given its own number, and these numbers do not change even if the source is mentioned several times.
An example of the CSE citation-sequence system: ... this aspect remains unchanged1.
- Title-year: in this system, references in the text are made by placing the author's name and year of publication in parentheses. In the list of references, the sources are arranged in alphabetical order by the author's last name. This style resembles the APA format, where the author and date are the main elements of the reference. This system allows the reader to easily find a source and assess its relevance.
An example of the CSE system is title-year: ... this aspect remains unchanged (Brown 2025).
- Citation-title: the list of references is first arranged alphabetically (by the name of the first author), and then each source is assigned a number. When citing sources in the text, use the number that corresponds to the number of the source in the list. For example, references in the text will look like (1), (2), and so on. This allows you to organise your references in alphabetical order, but at the same time simplify the references in the text itself.
An example of the CSE system: ... this aspect remains unchanged (3).
In this case, the literature used was previously arranged alphabetically, and only after that it received its own serial number – 3.
There are also a number of requirements for the bibliography, which is located at the end of a research paper. In order to find the rules for referencing a source in the CSE format you need, follow this link.
3. Chicago
Chicago Style – is a universal bibliographic reference style that is widely used in various fields, including history, social sciences, arts, and humanities. As in the case of CSE, it also provides for several approaches to citation: the author-date system and the notes and bibliography system.
- Author-date: this option is somewhat similar to the CSE title-year system. In this case, in-text citations are also made in parentheses, with the author's name and year separated by a comma. At the end of the work, all sources mentioned in the text are listed in the bibliography in alphabetical order by the author's last name with full information, including the year of publication, title of the work, publisher, and other necessary data.
An example of the Chicago Style author-date system: ... this aspect remains unchanged (Brown 2025).
- Notes and bibliography: citations in the text are given in the form of numerical notes (at the bottom of the page or at the end of the chapter) containing full information about the source. At the end of the paper, a complete list of references is also provided, including all the sources used in the paper. This style is often used in the humanities, such as history and literary studies, as it allows for a more detailed presentation of sources without overloading the main text.
An example of Chicago Style notes and bibliography:
"Research on climate change shows a significant impact of human activity on the environment, and this aspect remains unchanged1."
Note (bottom of page):
- John Brown, The Impact of Climate Change on Environment (Chicago: University of Chicago Press, 2025).
The bibliography is provided in alphabetical order by author's name (at the end of the paper):
- Brown, John. The Impact of Climate Change on Environment. Chicago: University of Chicago Press, 2025.
To find the rules for referencing a source in Chicago Style, follow this link. However, it should be noted that you must first register on the website.
4. Vancouver Style
Vancouver Style – is a powerful tool for citing references, especially in the fields of medicine and natural sciences. Its key feature is the use of numbered references, which makes the text concise and easy to read.
In the text of the paper, at the place where the source is cited, a number is given that corresponds to the serial number of the entry in the bibliography. This number may be given in different ways:
- (1) – in round brackets;
- [1] – in square brackets;
- ¹ – superscript digital index;
- [¹] – superscript digital index in square brackets.
Usually, the number is placed after the author's name or after a direct quotation, but it may also appear at the end of a sentence. It is important to note that when an author is mentioned in the text, only his or her surname is given. If the source has several authors, the surname of the first author is indicated with the addition of 'et al.
An example of citing a source in Vancouver Style:
Brown (1) states that this aspect is unchanged (1, p. 15).
And in the list of references, under number 1, there will be a full bibliographic description of this book:
- Brown J, The Impact of Climate Change on Environment. Chicago: University of Chicago Press; 2025.
It should be borne in mind that the choice of a particular citation style depends on the requirements of your educational institution or the research institution on the basis of which you are writing your research paper. To do this, consult with your supervisor at the stage of compiling the bibliography.
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