Look at your book.

A book publisher is often a good indication of its quality.

• Scholarly publishers print books written by professors and subject experts at universities and research centers. Scholarly publishers include university presses (MIT Press, University of Hawaii Press, University of California Press), scholarly and professional associations (American Psychological Association, American Medical Association), and commercial scholarly presses (John Wiley and Sons).
• Government and government agencies around the world publish documents of local, national and international interest (United States Government Printing Office, Center for Disease Control [CDC], National Space and Aeronautic Administation [NASA]).
• Mainstream commercial publishing includes fiction and nonfiction books intended for general audiences (Simon & Schuster, Viking).
• "Vanity" presses are profit-making ventures that will publish practically anything submitted to them for a fee.