 Hendrik Kloosterman

Hendrik Douwe Kloosterman (9 April 1900 – 6 May 1968) was a Dutch mathematician, known for his work in number theory (in particular, for introducing Kloosterman sums) and in representation theory.After completing his master's degree at Leiden University from 1918–1922 he studied at the University of Copenhagen with Harald Bohr and the University of Oxford with G. H. Hardy.