Among his teachers were Juliusz Schauder, Stanisław Mazur, Bronislaw Knaster, and Edward Szpilrajn, who organized a student conference in 1940 in Lviv, also attended by Stefan Banach.
Vishik then joined the retreating army and on foot reached Ternopil and then Zhmerynka (in Vinnytsia) and in two more weeks got by means of a freight train to Kiev.
He was a student at the pedagogical university in Krasnodar, but because of advancing German troops he then fled further to Makhachkala, where he studied for a year.
He received his doctorate in 1947 at the Steklov Institute of Mathematics,[4] and defended his thesis under Ivan G. Petrovsky and Sergey L. Sobolev.
His dissertation was a generalization of the work The method of orthogonal projection in potential theory[5] by Hermann Weyl, which he read with no knowledge of English.