Harriet Ziefert

Boon later obtained an attorney, Seth Salinger, through the Boston non-profit, "Volunteer Lawyers for the Arts." In 1999, Salinger filed a suit on Boon's behalf in Boston's federal court against Scholastic. Chuck Wentzel, a spokesman for Scholastic spokesman said, "Scholastic believes, based on our investigation, there was no copying done and that we will be successful in the litigation."

Ziefert and Boon have collaborated on a series of "Little Hippo" books, the first of which was published in 1988 by Viking Penguin. The books are written for children between 1 1/2 to 5 years-of-age. They are intended to help children deal with change, like the addition of a new baby to the family or moving to a new house. The hippo is drawn distinctively with stylized features, smudged outlines and light-gray coloring. In 1997, Boon saw a new series of "Little Hippo" books published by Scholastic, Inc. and claims that the characters are a take-off of her distinctive illustrations, use "Little Hippo" for its name and dress the hippo like hers. Further, Scholastic also sought to trademark the image of the hippo for a line of books. Some of the titles of the little hippo books are: "Daddy Can You Play With Me?" "Little Hippo's New Baby," "Little Hippo's New House," and "Mummy Where Are You?"

Harriet Ziefert (born July 7, 1941) is an American children's author. Ziefert was born in North Bergen, New Jersey. She has written several hundred children's books, including the Little Hippo series. Notable illustrators of her books include Emilie Boon and Santiago Cohen.