This is a statement. We don't know what you want to know, so if you can clarify it with a question we maybe able to answer.
Example sentence(s) - Childrens books are usually illustrated. I enjoy reading the childrens books to them.
Puffin Books.
Childrens books
childrens books
The questioner is working on the wrong end of the mystery. The far more useful question is: In children's books, why is the moon not white, like in the sky ?
he did write both
Nancy Drew books are children's books.
Frank Muir wrote the What-a-Mess children's' book range and it was illustrated by Joseph Wright. Hope that answers your question.
Richard Scarry
He is an author who writes childrens books
Author and editor of childrens books.
Writting Childrens Books!