Norton Anthologies - Edition Descriptions

[dojodo]

Where is a good source for "official descriptions" of Norton Anthology editions. Finding a lot of confusing data: Goodreads user notes this should be a 4th edition, Goodreads description says 6th edition, Amazon description says 7th edition, B&N identifies 4th edition with non-matching description referring to "Volume B" instead of "Volume 2"...

http://www.amazon.com/Norton-Antholog...

http://search.barnesandnoble.com/The-...