@article{DAN_1989_308_5_a0,
     author = {A. Yu. Daletskii},
     title = {The problem of factorization in a symplectic groupoid and},
     journal = {Doklady Akademii Nauk},
     pages = {1033--1037},
     year = {1989},
     volume = {308},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_308_5_a0/}
}