<A HREF="https://en.wikipedia.org/wiki/Alice_Roth">Alice Roth</A> became a mathematics teacher after her Ph.D. in 1938, and only returned to research after her retirement in 1971. Her <A HREF="https://dx.doi.org/10.4153/CJM-1978-103-4">1976 paper</A> on the "fusion lemma" is said to have "influenced a new generation of mathematicians worldwide".