Authors should look into copyrighting prior to printing their material.
Here are some resources that can help:
Cosynd and Bookbaby - https://www.bookbaby.com/cosynd/
Print Materials:
Copyright Clearance Center (CCC)
222 Rosewood Drive
Danvers, Maryland 01923
http://www.copyright.com
Although mainly for academic material, the CCC provides licensing for copyrighted materials in print and electronic form.
National Writers Union
http://www.nwu.org
U.S. Copyright Office, Library of Congress
http://www.copyright.gov