Hubert H. Humphrey (1911-1978), 1968 Democratic US Presidential Candidate, US Vice President under Lyndon B. Johnson, autograph on cover issued with a Special Film Tribute to the memory of Robert F. Kennedy. B&W cachet, signature in black felt tip pen at the 1968 Democratic Convention in Chicago. A very scarce cachet on cover dated August 26, 1968 and postmarked Chicago.  Fresh & VF.