There are several methods of distinguishing between all of the editions.                               The examples below are labeled 1 and 2.

In example 1.
This page can be found just near the front of the book.
The number at the bottom of the page 996.461. This tells you that the book was printed in April 1961.

  

 If this number is not present in this
 position, then you have to look at
  example 2. 

This can be found at the at  the bottom of the last index page. This again tells you the year the
book was printed. 614.1061 October 1961.

If the numbers are not present in examples 1 and 2 then quote example 3 below. This is the ISDN number and can also be found near the front of the book.