@article{DE_1999_35_12_a16,
     author = {A. N. Bobrov},
     title = {Letter to the editors: {{\textquotedblleft}The} trace of the {Laplace-Beltrami} operator with a potential on a {Zoll} surface{\textquotedblright} {[Differ.} {Uravn.} 35 (1999), no. 4, 528{\textendash}539, 575; {MR1719784]}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1713},
     year = {1999},
     volume = {35},
     number = {12},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1999_35_12_a16/}
}