Most copyright dates in a book are either in the very front of the book or the very back. There will be the publishing date and the copyright date. The copyright date is the one next to the "c" with the circle around it for copyright.
Each edition would have a different copyright date.
The copyright date is the year the text was completed. It may or may not be the same as the publication date.
1967- copyright renewed 1995
If a separate publication date is not specified, it can be assumed that it's the same as the copyright date.