@article{DE_1995_31_7_a20, author = {L. F. Yukhno}, title = {Generalization of the {Wittrick--Williams} method to nonlinear spectral problems with a multiple spectrum}, journal = {Differencialʹnye uravneni\^a}, pages = {1261--1264}, publisher = {mathdoc}, volume = {31}, number = {7}, year = {1995}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1995_31_7_a20/} }