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Chicago Manual of Style (English): Principles

Why cite?

Citing sources has multiple purposes:

  • It enables the reader of your work to check the information sources.
  • It shows that your work is based on academic literature.
  • It shows that an idea comes from another work. You can avoid plagiarism by citing the sources that you use.

Double citation

Citing sources according to the Chicago Manual of Style

The Chicago Manual of Style is used to cite literature and other sources that you used in your own text. You refer directly to literature and sources in your own text. At the end of the document, you provide a bibliography or reference list containing the sources that you used.

Citations in the text

The Chicago Manual of Style describes the rules for citing the literature you used in your text. Different rules apply for different publication types, such as books, journal articles, e-books, or web pages. These rules are very strict. 


In the bibliography at the end of the paper, the references will look different than those you placed in the text.

Two CMS styles

The Chicago Manual of Style describes two ways to cite sources:

I: Notes and Bibliography

II: Author-Date References

The style that you choose will depend on your discipline, the rules of your degree programme, the preference of your lecturer, and your personal preference. The first style, Notes and Bibliography, is typically used in the humanities, while the second style, Author-Date References, is used more often in the exact sciences and social sciences.

The biggest difference between the two styles is that you use footnotes and endnotes to reference your sources in Style I Notes and Bibliography, while you reference your sources by stating the author and year of publication in brackets in the body of the text in Style II Author-Date References. In both styles, you provide the sources you used in a bibliography.

Whichever style you decide to use, be sure that you follow the rules very closely and consistently. Every type of publication must be referenced differently. For instance, a reference to a book and an article from a journal look very different. The methods of citing the most common publications according to the CMS are addressed in this e-learning module. See the tabs at the top of the page for both systems.

Paraphrasing, quoting, and citing

The work of another author can be used in various ways in your paper:


What it entails:

What to do:


Using an exact text passage taken from the source

You state that you are quoting an author in your paper. You indicate that something is a quotation through formatting. At the end of the of the quotation, you cite the source.


Providing a summary of a text passage without adding your own opinion or interpretation.

You state that you are providing a summary of a text passage and cite the source.


Expressing the ideas or thoughts of someone else in your own words without adding your own interpretation or opinion.

You indicate that you are explaining the idea or thoughts of someone else and cite the source.

The style you choose from the Chicago Manual of Style will determine how a citation should look.