====De Graeff and William III of Orange====On 25 September 1660 the States of Holland under the prime movers of De Witt, De Graeff, his younger brother Andries de Graeff and Gillis Valckenier resolved to take charge of William III of Oranges education to ensure he would acquire the skills to serve in a future—though undetermined—state function.
(1995) "The dutch Republic - It's Rise, Greatness, and Fall - 1477-1806", Clarendon Press, Oxford, ISBN 978-0-19-820734-4* Rowen, Herbert H. (1986) "John de Witt - Statesman of the „True Freedom“, Cambridge University Press", ISBN 0-521-52708-2* Kernkamp, G.W.