This book is a compilation of several older stories by the famous American author/illustrator Richard Scarry (1919-1994), ranging from 1950 to 1968. This explains the variation in drawing styles and structure in the stories themselves. Apart from the great colours and compositions, the clarity in the stories and visual humour Scarry's drawing skills are just incredible! Every object is so well observed, the shapes,textures and patterns so accurate, yet the pictures appear to be simple and easy to the eye - just perfect for the young reader. Just look at those frogs above - exciting, funny and yet quite realistic! Classic.
A biography of the artist here: http://www.famousauthors.org/richard-scarry and on wikipedia: https://en.wikipedia.org/wiki/Richard_Scarry