The MLA Handbook (8th ed.) differentiates between core and optional elements. Core elements are required, as long as you can find the relevant information. Optional elements are—as the name implies—optional. This page provides some examples of the latter.
In some cases you may want to provide the original publication date. This information comes right after the title and before the first container:
Lively, William. The Spanish Comedy. 1598. Edited by Karen Sondheim, Oxbridge UP, 2014.
If you want to show where something has previously been published (e.g., for an article), use the tag “Originally published in”:
Chuckle, Hillary. “Ventriloquizing the Belly Laugh: An Ethnographic Perspective.” Recent Essays in Ethnography, edited by Boris London, Naked Truth Press, 2008, pp. 58-72. Originally published in ROFL, vol. 5, no. 1, Dec., 2005, pp. 1-14.
For books published prior to 1900 you are allowed to provide the city of publication rather than the publisher:
Murdoch, William. Four Constabulary Cases Selected for the Edification of the General Public. Toronto, 1897.
This is especially useful when you cannot find the publisher’s name.
In addition, if a book publisher has offices in multiple cities, or if you are citing a little known foreign publisher, you may provide a city name for clarification.
Fellows, Kimberly. Driven Over the Edge. New York, International Mystery Syndicate, 2005.
However, note that giving the city of publication is always optional.
For electronic sources you can provide a date of access. This date indicates when you consulted the electronic source for your research:
Beard, Stuart. “The Final Run.” Sofa Surfers, 8 Feb. 2017, www.sofasurfers.com/stories/the-final-run/. Accessed 20 Feb. 2017.
The date of access is useful because websites change constantly.
For multivolume works you would normally cite just the single volume you used. However, if you want to indicate the complete number of volumes in the series, you can add this at the end of the entry:
Devereux, Bob, editor. The Secret Correspondence of Elizabeth I. Vol. 5, Essex Press, 1991. 6 vols.
When a book is part of a series, you may include the series title and/or the number of the book:
Etui, Alice. The History of the Pencil Case. Oxbridge UP, 2016. Culture, Style, and Education 3.
If you have used a less than usual source, you may want to give a brief description at the end:
Flytrap, Venus. “The Science behind Trigger Warnings.” Mental Health and the Return to Nature. Peruvian Pavlovians Convention, introduced by Florence Wheelock, 3 July, 2009, Universidad Nacional Toribio Rodríguez de Mendoza de Amazonas, Chachapoyas, 2017. Presentation.
Other examples include transcript, lecture, and interpretive dance. Okay, we’re mostly kidding about the last one.
If you cite a bill, report, or resolution of the US Congress, you may refer to the Congress it came from, as well indicate what type and number of document you are citing:
United States, Congress, House, Oversight and Government Reform. Curtailing Trump’s Tweets. Government Printing Office, 2017. 115th Congress, 2nd session, House Report 592.
For more information on optional elements, please see pp. 50-53 of the MLA Handbook (8th ed.).