Multiple versions of the same edition of a textbook?

Question

In need of a textbook for my statistics class, and I always try to buy my books online as its typically a fraction of the price. However when I look for this book online, there are multiple versions of the same edition of the book. How do I know which is correct?

Here's a link to the book I need to get - http://www.hstbooks.com/buy_book_detail.asp?mscssid=ASA24XR8SQ3Q9HHLGF5B0Q35NJJGC10E&pf_id=10438060

And here's a link to the site I typically get my books from - http://www.directtextbook.com/search.php?qtitle=modeling+the+world&qauthor=bock&qpublisher=&qlanguage=&qkeywords=&qadvanced=Search

Should I just assume the first one listed is what I need? I guess I'm just thrown off by how each of the books listed have different number of pages, while being listed as the same edition & copyright year...

Answer 1

I only see one book on line with the same copyright year as listed in the requirements: 2007.

(You can safely ignore the teacher's edition.)