Combine different Editions of annual publications?

[Stephen]

If you look at this author you'll see that he has a number of books that he updates on a yearly basis. There are several editions for different years combined and others not. One way or the other this has gotta be wrong. What's the preferred method?

http://www.goodreads.com/book/combine...

[Cait]

The rule is to combine things which have the same content, even if the content is updated, and not to combine things which have new content on the same theme. Of course, that requires figuring out which category all of these guides fall into....

[rivka, Former Moderator]

I suspect it's category 1.

[MissJessie]

Yes, I'm the one who did it and that is how it struck me (#1).