What was the name of Roald Dahl's sister who died from appendicitis at age 7 in 1920?

Roald Dahl (13 September 1916 – 23 November 1990) was a British novelist, short-story writer, poet, screenwriter, and wartime fighter pilot. His books have sold more than 250 million copies worldwide. He was born in 1916 at Villa Marie, Fairwater Road, in Llandaff, Cardiff, Wales, to Norwegians Harald Dahl (1863–1920) and Sofie Magdalene Dahl (née Hesselberg) (1885–1967).

His first language was Norwegian, which he spoke at home with his parents and his sisters Astri, Alfhild, and Else. The children were raised in Norway's Lutheran state church, the Church of Norway, and were baptised at the Norwegian Church, Cardiff.

Dahl's sister Astri died from appendicitis at age 7 in 1920 when Dahl was three years old, and his father died of pneumonia at age 57 several weeks later. Later that year, his younger sister Asta was born. Dahl's mother decided to remain in Wales instead of returning to Norway to live with relatives, as her husband had wanted their children to be educated in English schools, which he considered the world's best.