Masha (Maria Simchow Stern) illustrated the very first Little Golden Book, Three Little Kittens in 1942. That is some claim to fame, however, there is virtually no information available about Masha. Considering that she had a "pen name," she must have wanted to stay anonymous.
In my book dealing, I have come across two titles by Masha from the '40s, The Child's Book of Bible Stories and the Child's Book of Prayers, published by Random House.
The illustrations in both of these books are so beautiful. The design enhances the art with gold borders and gold touches. Very sweet, innocent children, dreamy pastel coloring. Heavenly . . .
Here are some images: