I came across Costco editions of the following National Geographic books today. They each had a unique ISBN.
Thank-you for sharing this, Richard. Say, did they happen to look different . . . i.e., size, sans DJ's, different covers, etc.?
The Costco edition books are the same size as the previously issued hardcover editions. While these books have no dust jackets, their covers are the same as dust jackets on the previous editions. The front and rear covers on the Costco editions are not as stiff as a hardcover book but they are firmer than a paperback cover.