%0 Journal Article
%A N. P. Erugin
%T The Riemann problem. III.~The case $n=2$ and $m=4$
%J Differencialʹnye uravneniâ
%D 1977
%P 238-254
%V 13
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1977_13_2_a1/
%G ru
%F DE_1977_13_2_a1