@article{SM_1988_61_1_a7,
     author = {A. A. Borisenko},
     title = {On extremal properties of compact parabolic surfaces in {a~Riemannian} space},
     journal = {Sbornik. Mathematics},
     pages = {113--127},
     year = {1988},
     volume = {61},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1988_61_1_a7/}
}