Question: When did Princess Helena Adelaide Of Schleswig-Holstein-Sonderburg-Glücksburg's mother die?
Sentence (from "Princess Helena Adelaide of Schleswig-Holstein-Sonderburg-Glücksburg"): Princess Helena Adelaide of Schleswig-Holstein-Sonderburg-Glücksburg (1 June 1888 - 30 June 1962) was the third eldest daughter of Friedrich Ferdinand, Duke of Schleswig-Holstein and his wife Princess Karoline Mathilde of Schleswig-Holstein-Sonderburg-Augustenburg.
Relevant evidence: Yes