Books and essay collections in books are often very useful for finding criticism on authors and their literary works.  They often give overviews of an author's life and provide detailed discussion of an author's works.  Newer writers or less famous writers are often not covered in full-length books, but some books will include essays on wide range of authors.  To find criticism on a specific work by an author, you often will have to find criticism about the author and check the table of contents of index of books.

Most books of literary criticism will be in the 800 call number ranges shelved with books of literature (810s American literature; 820s British literature; 860s Spanish-language literature, etc.) on the 4th floor of the Library; see the Literature tab of this guide for how the call numbers reflect national literatures and genres.  Literary theory is often in the 800s, or in the different national literature call number ranges if that is the focus of the book.

To find books of literary criticism, you can use the Library of Congress subject headings (which are assigned to books to describe what they are about).  For books on authors, the subject headings often include the literary author's name and dates sometimes followed by "criticism" or "interpretation" or another related term, or the title of a literary work by the author.  The dashes indicate subdivisions by topic, time period, geography, etc.  You don't need to reproduce the exact format of the subject heading, but can use the terms in your keyword searches.  Examples of typical literary criticism subject headings are

Morrison, Toni--Criticism and Interpretation

Or for searches on topics:

African Americans in literature

Women and literature--United States--20th century

WorldCat (for books or media, not articles) is a catalog database of library holdings worldwide.  Use it to search for books NOT necessarily at the OSU Library.  Use the "Borrow from another library" link when viewing a book/media record to access the Interlibary Services loan form to request the book from other libraries; that service is free to OSU students, faculty, and staff, but the other library determines how long you can keep the item.