One day Wendy sees two guests in her apartment building. Only the guests aren't people . . . they're bears! Wendy can't believe her eyes. The bears are hiding in the building awaiting rescue from bears of outer space. She tries to keep them hidden, but it sure isn't easy.

The Bears Upstairs 1989, Scholastic

ISBN-13: 9780590425612

Trade paperback

The Bears Upstairs 1978, Greenwillow Books

ISBN-13: 9780688801694

Unknown binding