The book in question is Dale Carnegie's "How to Win Friends and Influence People".
This is a screenshot taken from the amazon listing of the book: https://i.imgur.com/pYt4ws9.png
This is the text as it appear in there,
Copyright © 1936 by Dale Carnegie.
Copyright renewed © 1964 by Dome Dale Carnegie and Dorothy Carnegie.
Revised edition copyright © 1981 by Donna Dale Carnegie and Dorothy Carnegie.
Dale Carnegie passed away on November 1, 1955. How was the copyright extended in 1964 and again in 1981 by Donna Dale Carnegie and Dorothy Carnegie (His wife and daughter)? Will they be able to do it again?
I was of the opinion that there is a fixed number of years for the copyright to naturally expire. In this case it should've been 95 years after publication.