@article{ZNSL_1997_239_a3,
     author = {M. I. Belishev and A. B. Pushnitskii},
     title = {On a triangular factorization of positive operators},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {45--60},
     publisher = {mathdoc},
     volume = {239},
     year = {1997},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1997_239_a3/}
}