Question: When did Flemming Topsøe's father die?
Sentence (from "Flemming Topsøe"): He is older brother of the engineer Henrik Topsøe (born 1944), son of the engineer Haldor Topsøe (1913–2013) and great-grandson of the crystallographer and chemist Haldor Topsøe (1842–1935).
Relevant evidence: Yes