Investigata a Ministerio Investigationis Foederali et ad HUAC vocata quia nomen anno 1936 fautor communista datum erat: Lucille Ball, FBI Records: The Vault, vault.fbi.gov (Federal Bureau of Investigation).
Freedom of Information/Privacy Act Section. "Subject: Danny Kaye". Federal Bureau of Investigation.
knaw.nl
dwc.knaw.nl
G. Alberts et W. T. van Est, "Leevensbericht Dirk Jan Struik," Huygens Institute - Royal Netherlands Academy of Arts and Sciences, 7.