Harder studied mathematics and physics in Hamburg and Göttingen. Simultaneously with the Staatsexamen in 1964 in Hamburg, he received his doctoral degree (Dr. rer. nat.) under Ernst Witt with a thesis Über die Galoiskohomologie der Tori.[1] Two years later he completed his habilitation.
For decades, Harder was known to German mathematicians as the Spiritus Rector for a mathematical workshop held for one week in spring and one week in autumn; the workshop, sponsored by the Mathematical Research Institute of Oberwolfach, introduced young mathematicians and scientists to important new developments in pure mathematics and mathematical sciences.[citation needed]
"Algebraische Zyklen auf Hilbert-Blumenthal-Flächen". Journal für die reine und angewandte Mathematik (Crelle's Journal). 1986 (366). Walter de Gruyter GmbH: 53–120. 1 March 1986. doi:10.1515/crll.1986.366.53. ISSN0075-4102. S2CID119657447. (online).
Bruinier, Jan (2008). The 1-2-3 of modular forms : lectures at a summer school in Nordfjordeid, Norway. Berlin: Springer. ISBN978-3-540-74117-6. OCLC233973403.[6] (contains Harder's contribution: Harder, Günter (2008). "Congruence Between a Siegel and an Elliptic Modular Form". The 1-2-3 of Modular Forms. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 247–262. doi:10.1007/978-3-540-74119-0_4. ISBN978-3-540-74117-6.)