The subtitle of the sixth edition of this book, now in electronic form, says it all: "An Annotated Listing of Reference Sources in English Literary Studies." Author James L. Harner has provided an exhaustive list of reference resources in all aspects of English literature studies. There are over 1000 annotated entries in this book that discuss over 1600 different books that cover topics from early English to 21st Century literature, poetry to Children's literature, and authors writing in English all over the world. This, along with the MLA International Bibliography database, should be the first resource consulted when starting research. The book can be accessed here.
TheDictionary of Literary Biographyis a series of volumes, each of which have a certain focus: genre, time period, author, nationality/ethnicity, etc. The online version, which can be accessed here, makes the entire series searchable. Every article in the DLB is bio-bibliographical in nature, meaning it discusses an author's work in terms of available biographical information. One author may be represented twice -- for instance, there may be an essay on James Joyce as a playwright and another on Joyce as a novelist, and yet another on him as a writer of short stories. This resource is every bit as important as the MLA International Bibliography for doing thorough research in English Literature.