The following titles can give you an excellent quick overview of literary concepts, major themes, national literatures, and major works and authors. They are great to use when looking for a brief initial introduction. Most research papers will require additional research into primary and secondary sources; these resources are great for helping initially familiarize yourself with a topic and developing a research hypothesis.
The Concise Encyclopedia of Modern World Literature.
Encyclopedia of World Literature in the 20th Century. Wolfgang Bernard Fleischmann, ed.
PN774.L4333 3 vols.
World Literature and Its Times
PN50.M625 4 vols.
Cassell's Encyclopedia of World Literature.
PN41.C3 1973 3 vols.
McGraw-Hill Encyclopedia of World Drama, Second Edition.
PN1625.M3 vol. 1-5
Princeton Encyclopedia of Poetry and Poetics.