For concise background information on German authors, it's hard to beat a series called the Dictionary of Literary Biography. The volumes on German authors are in the Reference Collection on the 2nd floor of Alden Library, mostly in the PT1 call number range and above. Each entry contains an overview of the author's life and writings, illustrations, and a bibliography which can lead you to more information on the author. Highly recommended!
Below are a couple of additional sources on literary history in the Reference Collection on the 2nd floor of Alden. Be sure to look in this same call number area on the 7th floor for many more books on literary history.
Here are a few additional sources on literary history: