Author Last Name, Author First Name. Source. Publisher, Date of Publication.
Morrison, Toni. Beloved. Alfred Knopf, 1987.
Singleton, Jermaine. Cultural Melancholy: Readings of Race, Impossible
Mourning, and African American Ritual. U of Illinois P, 2015.
MLA makes a distinction between online books and ebooks. Ebooks are normally downloaded onto personal devices, such as a Kindle Reader or iPad, and lack a URL.
MLA Handbook. 8th ed., e-book, Modern Language Association of America, 2016.
If you know the e-book provider, specify it:
MLA Handbook. 8th ed., Kindle ed., Modern Language Association of America,
2016.
"Ask the MLA." MLA Style Center, Modern Language Association of America, 2016,
style.mla.org/category/ask-the-mla/.