Peggy Parish is well known because of her Amelia Bedelia series of books. She had done 12 titles when she died suddenly. The publishers felt that the series could continue and Peggy's nephew Hermann decided to keep the series going. If you look at the Amelia Bedelia website you can see which are the twelve original titles and which are the newer ones.
Laura Numeroff is also well-known because of a series of books, her If You ... series. They were slow to come to Australia but now that they are here and have accompanying toys they are well-borrowed. The library has a large mouse toy to accompany If You Give a Mouse a Cookie and he makes the book even more appealing. As well as this series illustrated by Felicia Bond Laura has other books such as Beatrice Doesn't Want To and the popular new The Jellybeans and the Big Dance which are illustrated by Lynn Munsinger.