Sheet music for 'So Long' from Toy Story 3?

I've been loooking for the piano book for Toy Story 3, and when I finally found it online, So Long wasn't on the list of songs in the book. For some stupid reason, the book only has two songs from Toy Story 3, and then two other Randy Newman songs that weren't even in the movie. Does anyone know where I could find sheet music for 'So Long'?