I'm not sure if this is the edition I have

[Aaron]

I have a copy of this book, but my version doesn't have the 13 digit ISBN, it says it was released in 1989, whereas the version listed here says it was released a year later in 1990, and it has the secondary title, which is also listed on Goodreads under a different ISBN.

http://www.goodreads.com/book/show/87...

(That one has the same ten digit ISBN as my physical copy, but my copy's titles reads the same as the following link.

http://www.goodreads.com/book/show/13...

I'm wondering if all of these should be combined, and if I need to add a new edition, or edit the existing one with the same ten digit ISBN.

[Sandra]

I've combined them, all editions from 1972 to 1989 have the full name according to WorldCat.

WorldCat also confirms 1989 for your ISBN. Go ahead and edit the existing edition as there doesn't appear to be a 1990 edition.

[vicki_girl]

The editions are already appropriately combined. There is no need to add a new edition. Edit the record that has the same ISBN as your book.

[Aaron]

Thanks guys.