Jan Tresling (Winschoten, 8 March 1882 -- Hilversum, 15 April 1969) studied physics in Amsterdam, graduating in 1913. He held a position as technical assistent at the Technische Hogeschool in Delft, and conducted research on elasticity theory at Leiden University. His dissertation ("Deformaties en trillingen in het vaste lichaam bij afwijkingen van de wet van Hooke, ook in verband met de toestandsvergelijking") was defended on 9 July 1919, with professor Paul Ehrenfest as promotor. In a remarkable career switch, he then started the study of medicine, graduating in 1934. He practised as a family doctor in Amsterdam. Note: The name Jan Hendrik August Theunes Tresling (found at various places on the internet) refers to a different individual (born 1874 rather than 1882). Carlo Beenakker Sources: https://www.delpher.nl/nl/boeken/view?coll=boeken&identifier=MMKB02:000122361:00168&objectsearch=Tresling https://www.archieven.nl/nl/zoeken?mivast=0&mizig=210&miadt=5&miaet=1&micode=585&minr=1185721&miview=inv2&milang=nl https://www.ntvg.nl/system/files/publications/1969108170004a.pdf https://www.openarch.nl/gra:39e0fe36-7382-d18e-26eb-85f0fc785bfb https://www.openarch.nl/saa:e9e4c43d-69a7-4411-b632-f0f10d6bad88 https://ilorentz.org/IL-publications/dissertations/sources/Tresling_1919.pdf