Publication Manual of the American Psychological Association (7th ed.) by Published by the Modern Language Association (MLA), the MLA Handbook is the most authoritative resource for organizing your paper and citing sources, using MLA style. The newest copy is available at the Bierce Library's Services Desk in print and as an eBook:
MLA Handbook, 9th ed. (2021) by 
MLA Handbook (2021, 9th edition) by