Widerberg was behind several anthologies, collections of poems and picture books for children and young people.
She became best known for the anthologies "Love and Rebellion" and "The Children's First Book".
The latter was distributed to all newborns in several municipalities and became a classic.
The debut took place in 1966 with "Gertrud på daghem", a book for children who would start preschool.
In the 80's, she attracted attention with the books about Hasse, whose parents were alcoholics.
Siv Widerberg passed away on Christmas Eve after a period of illness, relatives tell TT.
She turned 89 years old.