@article{MZM_1998_64_1_a0,
     author = {D. N. Azarov},
     title = {On the residual nilpotence of free products of free groups with cyclic amalgamation},
     journal = {Matemati\v{c}eskie zametki},
     pages = {3--8},
     publisher = {mathdoc},
     volume = {64},
     number = {1},
     year = {1998},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1998_64_1_a0/}
}