Werner Ziesel has built up a collection of about 1300 mainly rare historical children's and youth books over many years of collecting. His historical collection contains mainly first editions and early editions from German-language publishers from the publication years 1550 (Johann Meckhart: Ain Christliche ainfältige, und zu dieser Zeit seer notwendige ermanung, an die jugent, darin angezaigt wird, was darin darin angezaigt, was die Kinder zuthun ihren Eltern zutun se se sein) until 1924.
The collection focuses on genres such as ABC books, employment books, picture books, fables, sagas, folk books, children's songs, nursery rhymes and poems, travel and adventure books, stories, moral and religious instruction, books on reality, children's magazines, and an almost complete internal collection of the works of Franz von Pocci.
Numerous books in the collection contain valuable illustrations, for example in Art Nouveau, and interesting examples of the development of reproduction techniques.
Werner Ziesel has given this collection to the International Youth Library in 2019, initially as a deposit.