Most libraries will have access to other resources about literature, including the Contemporary (and other) Literary Criticism series, Contemporary Authors, Something about the Author, etc. Depending on the library, these may be available online-- or not. Be sure to check to see what resources the library/libraries you use have!
Most statewide library consortia make available specified search engines for elementary and high school students, which often provide content specified to a certain reading/understanding level. Here are some examples that we have through the Jerseyclicks (New Jersey State Library) database selection
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Drew University Library, http://www.drew.edu/library