Electronic Journal of Differential Equations,
Vol. 2001(2001), No. 43, pp. 1-5.

Title: Two symmetry problems in potential theory
        
Author: Tewodros Amdeberhan (DeVry College of Technology, North Brunswick NJ, USA)

Abstract: 
  We consider two overdetermined boundary value problems
  as variants on J. Serrin's 1971 classical results and prove
  in both cases that the domains must be Euclidean balls.
  
Submitted February 13, 2001. Published June 6, 2001.
Math Subject Classifications: 35N05, 35N10.
Key Words: Overdetermined problems; maximum principles.