@article{10_4153_CJM_1992_033_0,
     author = {Gupta, C. K. and Gupta, N. D. and Roman'kov, V. A.},
     title = {Primitivity in {Free} {Groups} and {Free} {Metabelian} {Groups}},
     journal = {Canadian journal of mathematics},
     pages = {516--523},
     year = {1992},
     volume = {44},
     number = {3},
     doi = {10.4153/CJM-1992-033-0},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1992-033-0/}
}