@article{ZNSL_1983_132_a18,
     author = {V. M. Tsvetkov},
     title = {The complement of relations in pro-$p$-groups of cohomologioal dimension two},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {172--177},
     year = {1983},
     volume = {132},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1983_132_a18/}
}