By Molly Daly

PHILADELPHIA (CBS) - Fans of writer and illustrator Maurice Sendak are in for a treat.

A new exhibit at the Rosenbach Museum follows the author’s creative process — “Pen to Publisher: The Life of Three Sendak Picture Books” runs through July 15th.

“Here at the Rosenbach, we have the world’s biggest collection of Maurice Sendak’s artwork, author of “Where the Wild Things Are,” and “In the Night Kitchen,” and almost a hundred other picture books.”

The Rosenbach’s Patrick Rodgers says the show covers  “The Sign on Rosie’s Door,” “Outside Over There,” and “Brundibar.”

“This exhibition brings out the stories that went into each of those books’ creation.”

And he says there’ll be surprises.

“When he was working on his book “Outside Over There,” he would write down little scraps on his calendar pages. So we’ve got this little display of February 3, 1977 calendar page — just a small little note, and then all over it it’s got these different scribblings about goblins and things like that.”

Rodgers says it shows that creating anything is messy.