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Albert S. Cook Library

ACS Style

Learn to cite sources using American Chemical Society (ACS) Style.

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In this guide

Examples on this page are based on the The ACS Guide to Scholarly Communication (2020). Remember, your professor is the final authority for the bibliographic form, including spacing used in your paper.

ACS Style Guide

In-text Citations

There are three ways to cite references in-text using ACS Style. Select ONE in-text style to use consistently throughout your paper.

 

Superscript numbers - In-text citations are superscript numbers. References are listed at the end of the paper in the order in which they have been cited. If you are citing more than one reference in the same phrase or sentence, separate the superscript numbers with a comma (eg: 1,2). If three or more are used in sequence, include the first and last numbers and separate them with a dash (eg: 1-3). If a reference is used more than once, it keeps the same superscript number throughout your paper.

Example: Smith et al. discovered similar results.A variety of other studies found conflicting results, however.3-5,10,11

 

Italicized numbers in parentheses - In-text citations are italicized numbers in parentheses at the end of the cited phrase or sentence. References are listed at the end of the paper in the order in which they have been cited. If you are citing more than one reference in the same phrase or sentence, separate the superscript numbers with a comma (eg: 1,2). If three or more are used in sequence, include the first and last numbers and separate them with a dash (eg: 1-3). If a reference is used more than once, it keeps the same superscript number throughout your paper.

Example: Weber and Mathews reported related findings (9). Several other recent studies (3-5, 10, 11) indicate that...

 

Author and date in parentheses - In-text citations consist of authors' last names and the year of publication. If a source has two authors, include both last names with the word "and" in between. If a source has three or more authors, include only the first author's name, followed by "et al." If you are citing more than one references in the same phrase or sentence, list the references alphabetically in the same set of parentheses and separate them with a semi-colon. If you introduce the author's name in your sentence, then your in-text citation only needs to include the year. References are listed at the end of the paper in alphabetical order by the author's last name.

Example: ... the binding behavior of BaP-linker haptens (Chen and Pellequer, 2004). Smith (1998) draws similar conclusions, but three other studies had results that appear to conflict with these findings (Axelrod, 2003; Cobbs and Stolman, 2005; Gerson et al., 2001).