In 1952 Heegner published what he claimed was the solution of a classic problem proposed in the works of seminal mathematician Gauss', the class number 1 problem, a significant and longstanding problem in number theory. Heegner's work went unnoticed for years, due partly to a few minor mistakes in the paper which distracted or distorted critiques of his work, partly to his refusal of invitations to speak publicly on his work, and partly to professional/academic mathematicians' reluctance to accept the work of an amateur. Heegner's proof was finally recognized in 1967 when Harold Stark independently arrived at a similar proof, which was shown to be equivalent to Heegner's.
- Kurt Heegner. "Diophantische Analysis und Modulfunktionen." Mathematische Zeitschrift, (56):227–253, 1952.de:Kurt Heegner