Question: What is the date of death of Count Oluf Of Rosenborg's mother?
Sentence (from "Count Oluf of Rosenborg"): (Oluf Christian Carl Axel; 10 March 1923 – 19 December 1990), a former Danish prince, was the younger child and son of Prince Harald of Denmark by his wife, Princess Helena Adelaide of Schleswig-Holstein-Sonderburg-Glücksburg.
Relevant evidence: Yes