What stands out is the illustrated slipcase that holds the set.
ArchivesP.D. Eastman
The Big Blue Book Of Beginner Books – Hardcover – 367 Pages (6 Books in 1)
This novel is a study in restraint, saying much with very little.
P.D. Eastman Bright and Early Board Books 6 Book Set NEW
You will find that the illustrated appendix adds extra depth.