How do you find out if you mention a name in your book you have to get permission from an author or estate?

Names of people are not usually copyrighted. Not usually, but never. To mention someone's name in a book, no permission has to be obtained from an author or from his estate unless his or her private life is discussed or dissected instead of public life. Address of an author or that of his estate will be recorded in any of his books as the copyright holder of that book, where permission, if needed, can be requested.