The style of the Modern Language Association (MLA) is purported to be popular in universities and secondary schools. How the MLA got their style so widely accepted is beyond me. (In full disclosure, I am a Bluebook fan.)
The MLA used to publish both a Handbook and Manual of its style. The Manual has been discontinued and the Handbook, currently in its 8th Edition, is the "authoritative" statement of MLA Style. The MLA Handbook is typically found at call number LB2369 .G53 at academic libraries. You can also purchase it directly from the MLA or from your book retailer of choice.