These books really pop.

Puget Sound’s Archives & Special Collections recently acquired 150 pop-up books, donated by retired art librarian Stanley Hess of Bremerton, Wash. Pop-up books, which date to the 13th century, are intricate—their authors are often referred to as “paper engineers”—and highly interactive. The books are popular not just with kids but also art lovers and book collectors. You can read more about the new Puget Sound collection, including an interview with Hess, at the library’s blog Collins Unbound. Here are some of our favorites from the collection.