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Research: Chicago Referencing Style: Chicago style with footnotes

Chicago is a referencing system that uses a noting technique. This guide is intended for IB Diploma Programme students.


If you use a footnote option, all relevant information about a source of information is given at the bottom of the page of your text where you refer to the information. 

When you use a source of information, you signify this in your text by using a number, starting with 1, at the end of the sentence (or clause of a longer sentence) in which the source of information is used. 

The number is placed by superscript, e.g. ¹. (There should be a footnoting option in the Word document you're using.)

The note (with details about the source of information) appears at the foot or bottom of the same page as that in which you refer to the source of information. 

When you quote someone, the note number appears immediately after the quote, e.g. "the solution thickened and turned purple."¹

If you use a source consecutively, you need to use separate numbers. When this happens, you can use the abbreviation '"Ibid", which simply means that it is the same source as the last footnote entry. 

When you use a source more than once, you do not need to give the same details twice, just a shortened form will suffice. An online citation generator (e.g. EasyBib or Zotero) may be able to help with this. However, in your planning and drafting of your work, you may wish to keep the full details with each numbered note.  

What do footnotes look like?

In the footnote, an entry should appear in a similar format to this example (for a book):

   1. Stella Cottrell, The Study Skills Handbook (London: Palgrave Macmillan, 2008), 45. 

In this example, the number is in regular font size; the author's name appears next, followed by the title (in italics), followed by the place of publication, publisher, and date of publication (in parenthesis), with the page number given last. 

Here is another example, this time of a website:

   2. National Environment Agency, "PSI Readings", Singapore Government, (accessed March 26, 2014), 

"Accessed" refers to the date you looked at or used the website. The URL is listed last. A URL by itself is not an acceptable means of citation in the Chicago style.

For an interview you carry out, the note details should be similar to this example:

   3. Martin Chen (Managing Director, InfoSpace Ltd.), in discussion with the author, May 2013.

The person you interviewed appears first, then her/his title or work function. The author is you. The month and year refers to the time when you carried out the interview. If you make further references to the interview, you do not need to include all the details, just a shortened form, e.g.

   7. Chen, interview.

The number refers to the next time you use the interview, followed by the interviewee's family name, then the type of information you have used. 

Can I use the same number later in the text?

You cannot re-use a number later in your text. If you refer to a source of information you used earlier, you still need to use the next available (i.e. sequential) number to record your use of the source of information at that point in your text.

Common Problem

I'm using footnotes, but am told that my references are in MLA style. Why is this?

This is probably because you have used EasyBib, or another free citation generator on the Internet. These free sites generally only allow you to reference in one way - usually MLA. If you're using footnotes, you need to use a style called Chicago. 

What can you do about it?

1. Use the costed version of EasyBib (the College pays, so you don't have to). If you do this, you can choose your referencing style. See the Libguide on EasyBib for further information. 


2. Change to MLA style. Put the references in one list, with the heading "Works Cited", at the end of your essay AND, instead of using numbers in superscript in the text, include an in-text reference in brackets or parenthesis in its place. Therefore, you don't need numbers  in the text, nor footnotes. If you're unclear about how to follow this advice, ask the Librarian and/or see the libguide on MLA

What to check before submitting your work

Make sure that the number in the text corresponds to the number at the bottom of the same page and that the information given refers to that source of information. 

Is it possible to include further information in footnotes?

Yes, it is possible to do this, but use it with care, and follow these points:

1. Think of a way of incorporating your information in the text itself. Examiners do not have to read long footnotes. If the information is important, put it in the text. If it isn't important, then leave it out.

2. Excessively long footnotes suggest poor drafting skills. 

3. When you include information as well as citation details in footnotes, check and double check that all your sources have been recorded in footnote form, as it is easy to overlook them, especially when you have redrafted your text.

4. Check your footnotes for accuracy. It is all part of your text and therefore your submitted work. Don't rely on the function in Word to do this for you.  

Using ibid.

In Chicago style, you can use the term 'ibid.' for citing the same source (used twice or more in succession) in your text.

As it is an abbreviation, a period or full-stop should be used after the d.

You should avoid using ibid. to refer to footnotes that do not appear on the same page.