In 1940 he was appointed professor in the University of Szeged and in 1967 moved to the Mathematical Institute of the Hungarian Academy of Sciences in Budapest.

He proved important results concerning the invariants of the class groups of quadratic number fields.

[1] In several cases, he determined if the ring of integers of the real quadratic field Q(√d) is Euclidean or not.

This led him to the investigations of lacunary polynomials over finite fields, which he eventually published in a book.

This work on lacunary polynomials has had a big influence in the field of finite geometry where it plays an important role in the theory of blocking sets.