@article{ZVMMF_1991_31_7_a14,
     author = {M. G. Giorgadze and A. D. Myshkis},
     title = {On the isoperimetric extremum of an eigenvalue},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {1089--1091},
     year = {1991},
     volume = {31},
     number = {7},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_1991_31_7_a14/}
}