How to cite a Project Gutenberg book in MLA Style?
MLA Style recommends citing a Project Gutenberg book as follows:
Author last name, Author first name. Title of Book. Project Gutenberg, Publication/Updated date, URL.
Robert, Henry. Robert's Rules of Order: Pocket Manual of Rules of Order for Deliberative Assemblies. Project Gutenberg, 13 Nov. 2004, https://www.gutenberg.org/ebooks/9097.
If you need further help, contact a librarian.