1. He received his doctorate in 1961 in Leiden from Willem Titus van Est (1921-2002) and Jacob Murre with thesis Reducible and Multiple Algebraic Curves, but had previously studied under Jean-Pierre Serre in Paris and Aldo Andreotti in Pisa.

Er promovierte 1961 in Leiden bei Willem Titus van Est (1921–2002) und Jacob Murre (Reducible and Multiple Algebraic Curves), war aber auch zuvor bei Jean-Pierre Serre in Paris und Aldo Andreotti in Pisa.