question: What is the date of birth of Prince Bernhard Of Orange-Nassau, Van Vollenhoven's father?
context: Title: Pieter van Vollenhoven
  Passage: Pieter van Vollenhoven Jr. (born April 30, 1939) is the husband of Princess Margriet of the Netherlands and a member, by marriage, of the Dutch Royal House.
  Title: Prince Bernhard of Orange-Nassau, van Vollenhoven
  Passage: Prince Bernhard Lucas Emmanuel of Orange-Nassau, van Vollenhoven (born 25 December 1969) is the second son of Princess Margriet of the Netherlands and Pieter van Vollenhoven. Before the succession of his cousin Willem-Alexander as King, he was a member of the Dutch Royal House and eleventh in the line of succession to the Dutch throne. With Willem-Alexander's succession however, he is no longer a member of the Dutch Royal House, and is no longer in line to direct succession to the Dutch throne, but still retains its membership as a member of the Dutch Royal Family
answer: April 30, 1939
citations: Pieter van Vollenhoven Prince Bernhard of Orange-Nassau, van Vollenhoven