%0 Journal Article
%A Grammatikopoulos, Myron K.
%A Hristov, Tzvetan D.
%A Popivanov, Nedyu I.
%T On the singularities of 3-D Protter's problem for the wave equation
%J Electronic Journal of Differential Equations
%D 2001
%V 2001
%I mathdoc
%U http://geodesic.mathdoc.fr/item/EJDE_2001__2001__a177/
%G en
%F EJDE_2001__2001__a177