@article{VMUMM_1990_4_a0,
     author = {B. Shmuttsler},
     title = {Estimates for the number of points of the negative spectrum of a class of pseudodifferential operators},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {3--5},
     publisher = {mathdoc},
     number = {4},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1990_4_a0/}
}