Willem Hendrik Keesom pronunciation http://forvo.com/word/willem_hendrik_keesom/
Voiceless E http://www.heardutchhere.net/lesson4.html#voicelessE
Guenault, Tony (2003). Basic Superfluids (First ed.). London: Taylor & Francis. p. 25. ISBN 0748408916. Retrieved 2 May 2020. 0748408916
"Willem Hendrik Keesom (1876 - 1956)". Royal Netherlands Academy of Arts and Sciences. Retrieved 28 July 2015. http://www.dwc.knaw.nl/biografie/pmknaw/?pagetype=authorDetail&aId=PE00001218