Over many years of collecting, Werner Ziesel has built up a collection of around 1,300 mainly rare historical books for children and young people. His historical collection contains mainly first editions and early editions by German-language publishers from the years of publication from 1550 (Johann Meckhart: Ain Christliche ainfältige, und zu dieser Zeit seer notwendige ermanung, an die jugent, darin angezaigt wird, was die Kinder ihren Eltern zuthun seind) to 1924.
The collection focuses on genres such as ABC books, activity books, picture books, fables, sagas, folk books, nursery rhymes and poems, travel and adventure books, stories, moral and religious instruction, non-fiction books, children's magazines and an almost complete collection of the works of Franz von Pocci.
Many of the books in the collection contain valuable illustrations, for example in Art Nouveau style, and interesting examples of the development of reproduction techniques.
Werner Ziesel initially left this collection to the International Youth Library as a deposit in 2019, then donated it to the International Youth Library Foundation in a ceremony on 24 May 2022. The collection is gradually being catalogued and can be searched in the OPAC-search field „shelfmark“ with the search term: ZIE/* .