Cambridge Companions offer many titles of relevance to French literary studies (and only a selection is offered here). Not only are there companions to particular authors such as Baudelaire, Flaubert, Zola but also on more general topics such as the French novel, French culture or medieval French literature.
This is only a very small selection of encyclopedias that UBC Library has on French literature and literary theory. Search the Library Catalogue - using either the term encyclopédie or encyclopedia and your topic for further results.