%0 Journal Article %A M. A. Mustafin %T The Riesz basis of the Bitsadze–Samarskiǐ spectral problem with infinitely multiple eigenvalues %J Differencialʹnye uravneniâ %D 1989 %P 172-174 %V 25 %N 1 %U http://geodesic.mathdoc.fr/item/DE_1989_25_1_a22/ %G ru %F DE_1989_25_1_a22