@article{AL_2013_52_4_a4,
     author = {V. A. Roman'kov and N. G. Khisamiev},
     title = {Verbally and existentially closed subgroups of free nilpotent groups},
     journal = {Algebra i logika},
     pages = {502--525},
     publisher = {mathdoc},
     volume = {52},
     number = {4},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_2013_52_4_a4/}
}