For her "lasting contribution to children's literature" she received the international Hans Christian Andersen Medal in 1990.
Michael Neugebauer Verlag published Zwerger's first book, Das Fremde Kind in 1977.
Zwerger continued to work with Neugebauer, who also occasionally contributed to the lettering and book design.
[3] Her style is similar to that of English illustrators of the 19th century and she acknowledges being influenced by the work of Arthur Rackham.
[1][2] She has also been honored at the Bologna International Children's Book Fair and the Biennial of Illustrators at Bratislava.