Best Ways to Cite Sources: MLA, APA, and Chicago Style

Citing sources in academic or professional work is a difficult concept to master. There are several different types of citation styles and each one has different rules for in-text citations, footnotes, end citations, and proper accreditation of sources. The citation styles also vary based on the type of source you are referencing.

To make things more complicated, different industries tend to prefer different citation styles. You might have learned how to cite original sources in high school or college, but if you’re suddenly writing an APA or Chicago style professional paper, you’re probably a little lost. 

Citations are essential because they prevent plagiarism. Stealing someone’s ideas, even unintentionally, is extremely illegal and punishable both academically and professionally. To avoid this, it’s essential to correctly cite your sources for any information that is not common knowledge. Here is a complete guide to MLA, APA, and Chicago style citations, to aid as you put your research together. 

Overview of Styles

The three main citation styles are APA, MLA, and Chicago style. While there are multiple different citation styles, these three are most commonly used in academic and professional writing settings. They vary widely from each other, and the differences are essential to know when you are writing. 

There are two main types of citations to worry about: in-text citations and end citations. In-text citations are generally shorter to reference a work or author’s name without taking up much space in the text itself. End citations usually give all the details about the text so an interested reader can find it later. 

In all three citation styles, in-text citations are backed up by a reference list or bibliographic citations. How the citations themselves are formatted differs per style, however. 

APA style papers have the most lengthy in-text citations, with the author’s last name, date published, and page or paragraph number of the idea or quote. If some of this information is included in the sentence, it’s not always necessary to put it in the parentheses

For MLA style citation, in-text citations include the author’s last name and page number of the quote or idea. At the end of the paper, a “works cited” page must be organized by the last name of the author and include all the relevant information. 

Chicago style is a little more complicated, as there are two sub-styles within it. With the author-date style of the paper, Chicago papers will include the author’s last name and year of publication in parentheses after the quote or idea. These in-text notes correspond to an in-depth citation page at the end.

However, some Chicago-style papers use a footnote and bibliography system, wherein the writer cites each source in a footnote or endnote and includes a separate references page at the end. This method is usually preferred if the sources aren’t as easy to date. 

Best Citation Styles by Industry

Of course, there is a reason for the various citation styles. Different industries use the styles to reflect the type of information they try to convey. APA is generally used in the sciences, math, and engineering, while MLA is popular with humanities, language, and literature. Chicago style is most common in publishing or journalism. 

Whether it is professional or academic writing, these styles reflect the industries in which they are prominent. For example, this APA-style paper on butterfly migration uses the names and years of the authors to identify how recent the research is and how relevant to current scientific data. 

MLA academic writing is utilized heavily by the humanities, history, literature, and language. This preference is because the sources aren’t as simple to date and are often other academic sources. It’s easier to find author names, and the relative newness doesn’t matter as much. Check out this academic paper on the classic novel Jane Eyre for an example. 

Chicago style citations are similar to APA in that they do need to be relevant and new. The year is required, and Chicago style is one of the only citation styles to use footnotes regularly. Here is an academic paper on journalism that uses Chicago-style citations. 

APA Style

APA style is probably the most common citation style, especially in the social sciences, engineering, and math industries. If you are a science major and need to write papers, odds are you will be writing them in APA style

APA stands for the American Psychological Association and was established in 1929. This style made it easier for researching scientists to see where ideas were coming from and what historical science they were building on. Before 1929, scientific papers had no set rules for citing sources, so they varied widely. 

Since the first edition nearly 100 years ago, there have been six updated editions of the APA style manual. It’s necessary to periodically update the rules to include changing source material, such as online sources and more varied physical copies. 

To cite a source in the APA style, you first need to find some information on that source. If you have a book in hand or a PDF copy of it, it will be easy to find the author’s name and the publication date. You should use an in-text citation every time you reference a major idea or direct quote from any source that’s not original or common sense. For example, an APA in-text citation might look like this:

In The Alchemist, the main character asks, ‘Where is the treasure?’ (Coehlo, 1988).

This citation directly quotes the work and gives the author’s last name and the year. If there were multiple authors, both their names would be required in the parenthetical citation

At the end of the research paper, the proper citation for the book would look like this: 

Coehlo, P. (1988) The Alchemist. HarperOne Publishing. 

This source is a very simple citation since the example is the hard copy of a book. However, with an online source, all you’d need to add is the DOI or digital online identifier. This identifier is generally a URL or link so that the reader can find the source if necessary. 

For more complicated sources or online journal articles, you can always turn to the APA citation style guide which can assist in clearing up any confusing aspects.

MLA Style 

The MLA citation style was created by the Modern Language Association in 1951. It originated as a simple instruction sheet on citing sources properly but soon grew into a small handbook. Now, the MLA style handbook is in the ninth edition and continues to adapt to modern language needs. 

MLA is primarily used by academics and teachers within the fields of history, language arts, and literature. The style was created for researchers and thesis writers and continues to be useful for less scientific research today. 

Just like in APA, it’s essential to avoid plagiarism as much as possible. Every time you use a paraphrase, a quote, or an idea from another source, you must provide proper in-text and end citations. If you aren’t sure whether you’re plagiarizing or not, ask a teacher or use an online plagiarism checker. Here is an example of an in-text MLA citation:

In The Alchemist, the main character follows the advice of an old man, who tells him to ‘never forget about his sheep’ (Coehlo 35).

In this sentence, the author paraphrases the main idea of the book and offers a direct quote. They then give the author’s last name and the page number where the quote is found. If the author of this thesis paper had referenced Coehlo in the sentence, it would only be necessary to put the page number in parentheses

Of course, MLA formatting requires works cited page at the end. The citation example for The Alchemist would look like this: 

Coehlo, Paolo. The Alchemist. HarperOne Publishing, 1988. 

This simple citation would be complicated if there were more components. For example, a web page or online source would need a DOI at the end. If it was a chapter in a book or a magazine article, the article title would be in quotation marks before the italicized title of the book. It’s always best to follow a complete citation guide when making citations. 

Chicago Style 

The Chicago manual of style is the oldest on this list and was first published in 1903. It was originally only used by the University of Chicago Press but soon grew to more academic journals and colleges around the country. 

Until relatively recently, the Chicago style of citations was the most common academic style for all disciplines. Now, however, Chicago-style academic works are used primarily for journalism and publication works. They are still occasionally found in history, humanities, and education papers. 

As previously mentioned, there are two types of Chicago-style papers: footnotes and bibliography or author and date. The footnotes and bibliography style are generally used for less scientific and more humanities-leaning academic papers, while author/date papers tend to be scientific and data-driven. 

However, the process for citations is relatively similar for both. The main difference is that the footnote and bibliography style in-text citations are limited to a superscript number, which corresponds to a foot or endnote in the paper. This note will have the author’s last name, the publications’ title, and the page number where the data is located in the paper. For example, an in-text footnoted citation might look like this:

The crux of the action happens when he says, ‘I am following my Personal Legend. It’s not something that you would understand.’⁶

Notice the superscript number 6 at the end of that example. At the bottom of the page (or the end), the note would look like this: 

    1. Coelho, The Alchemist, 134.

However, for author and date papers, an in-text citation would be more similar to APA papers:

The crux of the action happens when he says, ‘I am following my Personal Legend. It’s not something that you would understand.’ (Coelho, 1988).

This citation looks much more familiar and is easier for many people who have used APA formatting before. However, footnotes and bibliography are more common for Chicago-style papers. This is because it is a different style from many APA papers. 

Whether or not the in-text citations are author/date or footnote/bibliography, the end of your paper looks similar. It’s a little different if you use endnotes instead of footnotes, but you need a complete bibliography either way. 

An end citation for Paolo Coelho’s The Alchemist would look like this in Chicago style

Coehlo, Paolo. The Alchemist. HarperOne, 1988. 

As with MLA and APA formatting, a more complicated citation would need more information. If it’s a magazine article, the formatting is similar to MLA, with the article title in quotations marks before the book title. For an online source, a DOI and date of access are required. 

Final Thoughts

APA, MLA, and Chicago style citations are all simple enough to master. However, once you start to write papers for different audiences and across different industries, it can be stressful to keep them all straight. If you complete multiple papers with diverse citation styles, focus on one at a time so you don’t get confused. 

Citations are vital to your academic, professional, and personal writing life. Without them, plagiarism can sneak in even if you know where your sources originated. You must cite sources so that your audience can access them and know which of your ideas are your own. 

To ensure that you aren’t accidentally plagiarizing (after all, it’s easy to unintentionally take someone’s idea if you don’t know it exists), use Quetext’s online plagiarism checker. It will run your work through a database of hundreds of thousands of other papers, blog posts, and books to show you the final results. 

You can use the citation generator and plagiarism checker tools online to help you grow as a writer and a researcher. Instead of worrying that you might not be doing the correct format or using your own words well, let the experts at Quetext help you out and make your paper writing process smoother.