Gelberg founded in 1971 the children’s book series Beltz & Gelberg as part of the publisher Verlagsgruppe Beltz [de].[1] The initial eight books grew to 1000 titles in 25 years.[2] He published a magazine for youth literature, Der bunte Hund, around three times per year. He began a yearbook for children's literature in 1971, which appeared until 1999.[3] Since 1982, Gelberg collaborated with Achim Bröger [de], Janosch and Peter Härtling for individual issues of the magazine. Gelbert published work by writers for children including Josef Guggenmos [de], Nikolaus Heidelbach [de], Hans Manz [de], Erwin Moser, Christine Nöstlinger, Rafik Schami and Jürgen Spohn [de]. He lectured at the University of Frankfurt.[1] In 2011, he published an anthology of poetry for children, entitled Wo kommen die Worte her? (Where do the words come from?). It contains poems by more than 100 authors expressly written for the book, and also older poems by Christian Morgenstern and Joachim Ringelnatz, among others.[2]
Gelberg died on 17 May 2020 in a hospice in Weinheim, aged 89.[3]
