What Makes a Good Literature Paper? (Purdue OWL)
Literary criticism - found in books and journals - is the study, interpretation, and evaluation of a work of literature and of its author's place in literary history. Literary criticism of a work usually offers interpretation of its meaning, analysis of its structure and style, judgement of its worth by comparison with other works, and an estimation of its likely effect on readers. Literary theory (e.g., feminist, post-colonial, etc.) often informs the critical analysis of a literary work. Criticism may examine a particular literary work, or may look at an author's writings as a whole. See:
Writing a Literary Analysis (Purdue OWL)
Literary Criticism is not only found as essays from books but also as articles from Scholarly/Peer-Reviewed Journals. Articles (and often essays in books) of literary criticism are usually found through searching article databases. MLA International Bibliography is the best place to begin.
Scholarly vs. popular articles (from Vanderbilt University)
Criticism differs from book reviews in several ways: it entails both analysis and judgement; it may be published many years after a literary work is published; it is usually longer and more complex than a book review. A book review documents the critical reception of a book at its time of publication. It is usually more "consumer-oriented," i.e., placing more emphasis on recommendation than analysis.