In Göttingen Prasad showed his paper titled On the constitution of matter and the analytical theories of heat, the one he had submitted for the Adams prize competition, to Felix Klein, who appreciated it very much and got it published in the Göttingen Abhandllingen.
He was awarded a fellowship which enabled him to spend three years on graduate work; one year studying advanced mathematics under Felix Klein at Göttingen, one year studying electricity and mechanics under Ludwig Boltzmann in Vienna, and one year studying under Henri Poincaré in Paris.
Vidav got his Ph.D. under Plemelj's advisory in 1941 at the University of Ljubljana with a dissertation Kleinovi teoremi v teoriji linearnih diferencialnih enačb (Klein's theorems in the theory of linear differential equations).
Disillusioned with the state of mathematical research in North America at the time, he left for Europe in 1891, locating primarily in Berlin, Göttingen and Paris, where he associated with some of the greatest mathematical minds of the time, including Karl Weierstrass, Felix Klein, Ferdinand Georg Frobenius and Max Planck.
1917 — Albert Einstein and David Hilbert had dawn-to-dusk discussions of physics; and they continued their debate in writing, although Felix Klein records that they talked past each other, as happens not infrequently between simultaneously producing mathematicians.
Felix Mendelssohn | Calvin Klein | Felix Frankfurter | Yves Klein | Naomi Klein | Melanie Klein | Felix the Cat | Félix Guattari | Joe Klein | Ralph Klein | María Félix | Félix Trinidad | Felix Klein | Julie Felix | Felix Rodriguez | Félix Houphouët-Boigny | Felix Da Housecat | Calvin Klein (fashion designer) | José Félix Ribas Municipality, Aragua | Felix von Luckner | Felix Unger | Félix Rodríguez (Central Intelligence Agency) | Felix Magath | Félix Fénéon | Anne Klein | Allyson Felix | Allen Klein | Lawrence Klein | Joel Klein | Hans-Joachim Klein |
with David E. Rowe: The Emergence of the American Mathematical Research Community 1876–1900: J. J. Sylvester, Felix Klein, and E. H. Moore, AMS/LMS History of Mathematics 8, Providence/London 1994