1958-1959 - Zoo Guidebook
Ranney, Omar. Foreword by Harold T. Clark. Jim Herron, illus. Official Illustrated Guide to Cleveland Zoological Park. Cleveland: Max M. Axelrod, 1958 - 59 edition. When issued, the Zoo operated under the Cleveland Museum of Natural History and was known as the Cleveland Zoological Park.
Source:
Cleveland Zoological Park