The Chicago Manual of Style, 17th ed. (Chicago: University of Chicago Press), print or online version.
Amy Einsohn and Marilyn Schwartz, The Copyeditor’s Handbook: A Guide for Book Publishing and Corporate Communications, 4th ed. (Berkeley: University of California Press, 2019).
Erika Büky, Marilyn Schwartz, and Amy Einsohn, The Copyeditor’s Workbook: Exercises and Tips for Honing Your Editorial Judgment (Berkeley: University of California Press, 2019).
A recent edition of Merriam-Webster’s Collegiate Dictionary.
Barbara Fuller, How to Start a Home-Based Editorial Services Business (Guilford, Conn.: Globe Pequot Press, 2013).
Other dictionaries, including usage dictionaries, as relevant to your work (e.g., A Dictionary of Modern English Usage, Urban Dictionary, Stedman’s Medical Dictionary, Merriam-Webster’s Dictionary of English Usage).
Other style manuals, as relevant to your work (e.g., The Bluebook, Publication Manual of the American Psychological Association, The Gregg Reference Manual, Association of Art Editors Style Guide).
Patricia Heinicke Jr. has worked as a publishing professional for over 20 years, first in acquisitions at a small scholarly press and then as a freelance copyeditor, developmental editor, writing coach, and ghost writer. Her clients include authors of scholarly books and articles, biomedical abstracts and posters, and self-published memoirs and fiction. She has taught courses and workshops on copyediting, grammar, and other topics at Editcetera, UC Berkeley Extension, and Media Alliance and for corporate clients in the Bay Area and beyond.