Visit your local public library or elementary school library and borrow "Circus Shapes" by Stuart Murphy or "Circus of Shapes" by Kent Salisbury.
Contact or visit a major bookstore in your area to purchase either of the books listed above. If the store does not have the book(s) in stock, a staff member may be able to order one for you.
Shop at an online bookseller (e.g., www.barnesandnoble.com or www.amazon.com) by entering the name of the book, author or the keywords "circus" and "shapes" in the search bar. This will bring up whatever books they have available meeting these criteria, inform you whether the books are available and describe their condition and prices.
Shop in person or online at a retailer specializing in used books (e.g., www.alibris.com). This may be the best option for finding the Salisbury book, which is no longer in print.