The Find Text button (see below) lets you know whether full text is available. It opens new tab or window, taking you into the library catalog and showing options for accessing the resource under Get It. If one or more links appear under Get It, click any link with the correct date range access the item you want.
If no links appear under Get It and a yellow sign-in bar appears on the record page, log in with your Williams unix credentials and click “Request Scan” to request a copy through interlibrary loan (ILL).
You can also try Googling the citation: sometimes, copyrighted material is freely available on the web. Many journals are free, such as PNAS & PLoS. Some free versions of articles are preprints, with the figures at the end; these are acceptable.
Many of our databases have this 
button, which searches for the full-text of the article in our collections. If we don't have it electronically, look for the "Request article scan" link in the "Get It" section.
Unpaywall is an open database of millions of free scholarly articles. It includes open access content from over 50,000 publishers and repositories, and makes it easy to find, track, and use.