As with any academic work, you should always cite all of your sources and references.
You may notice that on some enotes study guides there's a set of Print - PDF - Cite - Link buttons at the top of the page (see picture).
If you click on the 'cite' button, a new window will pop-up.
For the Romeo & Juliet critical essay that's in the photo, the citation from the pop-up window is:
"Overview" Shakespeare for Students Vol. 1. Gale Cengage eNotes.com 23 Sep, 2015 <http://www.enotes.com/topics/romeo-and-juliet/critical-essays/criticism#critical-essays-criticism-overview>
This follows the standard form for citing websites, however, here the date of creation is missing.
If you have been asked to use a particular citation style, please refer to the manual for that style. If not, a bibliographic reference should include enough information that another can find the original reference. For websites, this should include the date of access, as unlike traditional print media, the content of websites is often fluid.
Therefore, if there's not a 'citation' button on a enotes page, you should reference the page including:
- author(s) name, including initials
- title of the article or essay (usually between quotation marks)
- title of the website (enotes) or journal, or 'umbrella brand'
- all other publication information (issue number, volume number)
- date of access/viewing
- the full URL (usually between pointed brackets '<>')