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/
Copyright Clearance Center (CCC)
222 Rosewood Drive
Danvers, Maryland 01923
Although mainly for academic material, the CCC provides licensing for copyrighted materials in print and electronic form.
National Writers Union
U.S. Copyright Office, Library of Congress