The books related to Literature are located in the P section of the Library of Congress (LC) Classficiation System. Where you'll find titles of interest depends of the type of literature you are researching. Here are the major LC categories for literature:
P (Language & Literature)
PN (Literature, General)
PR (English Literature)
PS (American Literature)
PZ (Juvenile Literature)
Listed are some possible keywords for a literature search:
Author's Name
Names of Characters in Text
Time Period of Text (20th century, etc.)
Genre of Text (Mythology, Science Fiction, etc.)
Type of Criticism (Textual, Feminist, etc.)
Themes Addressed in Text