Question: What is the date of birth of Prince Oskar Of Prussia's mother?
Sentence (from "Ernst-Johann Biron, Prince of Courland"): Peter Burchard, Prince Biron von Courland( born 6 August 1940) is the senior male- line descendant of Ernst Johann von Biron, and as such heir to the Duchy of Courland and Semigallia.
Relevant evidence: No