@article{ZNSL_1987_158_a7,
     author = {A. Yu. Zaitsev},
     title = {A generalisation of the triangle functions method},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {81--104},
     publisher = {mathdoc},
     volume = {158},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1987_158_a7/}
}