Question: Who is Duchess Altburg Of Oldenburg's maternal grandmother?
Sentence (from "Duchess Altburg of Oldenburg"): Duchess Altburg Marie Matilda Olga of Oldenburg (19 May 1903 – 16 June 2001) was a daughter of Frederick Augustus II, Grand Duke of Oldenburg by his second wife Duchess Elisabeth Alexandrine of Mecklenburg-Schwerin
Relevant evidence: Yes