@article{PIM_1986_N_S_40_54_a5,
     author = {Zoran Stojakovi\'c and Wieslav A. Dudek},
     title = {On {Sigma-permutable} {N-groups}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {49 },
     publisher = {mathdoc},
     volume = {_N_S_40},
     number = {54},
     year = {1986},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PIM_1986_N_S_40_54_a5/}
}