@article{MASLO_1979__29_1_a3,
     author = {Rach\r{u}nek, Ji\v{r}{\'\i}},
     title = {$Z$-subgroups of ordered groups},
     journal = {Mathematica slovaca},
     pages = {39--41},
     publisher = {mathdoc},
     volume = {29},
     number = {1},
     year = {1979},
     mrnumber = {561774},
     zbl = {0401.06010},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MASLO_1979__29_1_a3/}
}