@article{AA_1993_5_4_a3,
     author = {G. Sh. Guseinov},
     title = {Spectral analysis of second-order multiparameter differential equations with periodic coefficients},
     journal = {Algebra i analiz},
     pages = {98--121},
     publisher = {mathdoc},
     volume = {5},
     number = {4},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_1993_5_4_a3/}
}