Format: 

[1]F. Lastname, Full Tweet or "Title of post," Title of Website, Month Day, Year. [Online]. Available: URL, Accessed on: Month Day Year.

Examples: 

[1]Gibson, W. [@GreatDismal], Finally read a bit about Mr. Robot. How on earth did someone not manage to stop them using that title?, Twitter, Jul. 20, 2015. Dec. 12, 2017 [Online]. Available: http://twitter.com/GreatDismal/status/623319630115766272, Accessed on: Dec. 12, 2017.

Notes: 

Include the author's username in brackets after the author's name; if only the username is known, provide it without brackets as per APA style (see pg. 38, "On-Line Sources"). Consider including an access date for online materials particularly if the post might be removed or changed (see p. 39, "Reports and Handbooks," 2). The title of the post should appear in sentence case (i.e. only capitalize the first word and any proper nouns), while the title of the website should appear in title case (i.e. capitalize each word) (see p. 39, "Periodicals: Basic Format," 1). If you are citing a Tweet, use the full-text of the Tweet as the title of the post, but do not wrap it in quotation marks – follow the capitalization used in the post as per APA style (see pg. 38, "On-Line Sources").

Questions? Contact an RIT Librarian at libraryhelp@rit.edu

Source:
IEEE - Adapted from: Periodicals (p. 39)