Evaluating a source (a book or an article, for instance) begins with a critical look at the bibliographic citation--the written description of a book, journal article, essay, or some other published material that appears in a catalog, bibliography, or database.
Examine the publisher (name of the press or the journal publisher), date of publication, presence of an index and a bibliography, and author affiliations.
What can you deduce about the reliability of the source through this preliminary examination?
Learning how to determine the relevance and authority of a given resource for your research is one of the core skills of the research process.
For more assistance, consult your instructor or a reference librarian.