@article{DAN_1976_229_2_a5,
     author = {G. A. Isaev},
     title = {On multiparameter spectral theory},
     journal = {Doklady Akademii Nauk},
     pages = {284--287},
     publisher = {mathdoc},
     volume = {229},
     number = {2},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1976_229_2_a5/}
}