When in doubt, ask your instructor which citation style to use for your paper or project. Some of the most widely used citation styles include:

Since 2000 there has been an effort to assign everything that exists in the digital world, e.g. online articles, with a unique number called a Digital Object Identifier or a DOI.  The DOI is unique, permanent, and persistent. It remains the same despite changes in URL's or permanent removal from the Internet.

In APA and AMA citation styles, use the DOI in citations whenever one is listed.

When you cite a full-text article retrieved from a Webster University Library database, some citation styles require you to cite the database name and/or a URL. Here’s how the University's most-used citation styles address this issue:

• APA (7^th): Include only the Digital Object Identifier (DOI) if it is available. If there is no DOI listed in the database or on the article itself, do not include any database information or a URL.
• MLA (9^th), Chicago, AMA, Harvard: If a DOI is present, add both it and the database name to the citation. If a DOI is not present, include the database name and provide the database permalink or URL (if there is no permalink).
  • For help obtaining a permalink, view the FAQ: How do I find and use a database permalink?