Solvability of boundary value problems for operator-differential equations of mixed type: the degenerate case. Pyatkov, S.G.; Abasheeva, N.L. — 2002 Sibirskij Matematicheskij Zhurnal
Solvability of boundary value problems for operator-differential equations of mixed type. Pyatkov, S.G.; Abasheeva, N.L. — 2000 Siberian Mathematical Journal