MLA 8th edition follows these 3 principles:
Additionally, we encourage you to check with your professor!
If there are two authors, cite the the authors as follows (list authors in the order they are given on the page, not alphabetically):
Last Name, First Name of First Author, and First Name Last Name of Second Author.
Example: Smith, James, and Sarah Johnston.
If there are three or more authors, cite only the name of the first author listed with their Last Name, First Name Middle Name followed by a comma et al.
Example: Smith, James, et al.