Sergei Sobolev and Mikhail Leonidovich Gromov are not members of the IHS in Moscow.
Sergei Lvovich Sobolev (Russian:    ; 6 October 1908  3 January 1989) was a Soviet mathematician working in mathematical analysis and partial differential equations. 
Mikhail Leonidovich Gromov (also Mikhael Gromov, Michael Gromov or Mischa Gromov; Russian:    ; born 23 December 1943), is a French-Russian mathematician known for work in geometry, analysis and group theory. 
 He is a permanent member of IHS in France and a Professor of Mathematics at New York University. 
