Bill Martin Jr. books in order
8 books in the catalogue, about 4 hours of reading in all; the shortest takes 15 minutes and the longest 44 minutes.
8 standalone books in the catalogue.
Standalone books
Knots on a Counting Rope 35 min 
Brown Bear, Brown Bear, What Do You See? 32 min 
Chicka Chicka Boom Boom 44 min 
Chicka Chicka a B C 15 min 
Polar Bear, Polar Bear, What Do You Hear? 31 min 
Panda Bear, Panda Bear, What Do You See? 31 min 
Chicka Chicka 1 2 3 44 min 
Baby Bear, Baby Bear, What Do You See? 33 min