%0 Journal Article %A F. I. Frankl' %T An existence theorem for a~weak solution and first approximation of the direct problem in the theory of the plane-parallel Laval nozzle %J Izvestiâ vysših učebnyh zavedenij. Matematika %D 1959 %P 192-201 %N 6 %I mathdoc %U http://geodesic.mathdoc.fr/item/IVM_1959_6_a23/ %G ru %F IVM_1959_6_a23