Who illustrated "Exotic Zoology"? I love the illustrations in Willy Ley's _Exotic Zoology_ , which appear to be line art. Sadly my copy is a battered library-discard; either the front matter never attributed the artist or it was on a page that's now missing. Wikipedia and Goodreads say the artist was Olga Ley, but they don't offer any particular citation for the information and I can't find her name in searches of any of Wikipedia's reference links--so I don't know how much they suffer from ambiguous citogenesis. Who illustrated _Exotic Zoology_ and how do we know?

"A Bibliography of the Works of Willy Ley" (PDF link) was compiled by Jean M. Perreault for the Special Collections of the M. Louis Salmon Library at the University of Alabama in Huntsville after they acquired Ley's collection of books and journals upon his death in 1969 (link). It lists the illustrator of _Exotic Zoology_ (1959, 1st printing) as Olga Ley.

I think this is as definitive as it's reasonable to get without an edition to hand that makes the attribution itself (which is an answer I'd love to see, especially if it can say which edition!); while the claims made by Wikipedia and Goodreads concur that Olga Ley is the illustrator, they don't offer any support or citation for their claims. The UAH Library's commissioned bibliography of their own collection, on the other hand, can be considered the next best thing to an original source.