@article{MV_1969_21_2_a1,
     author = {K. U\v{s}an},
     title = {Nekotorye zamechaniya o poluklikah i opredelenie {AF-polugruppy}},
     journal = {Matemati\v{c}ki vesnik},
     pages = {117 },
     publisher = {mathdoc},
     volume = {21},
     number = {2},
     year = {1969},
     url = {http://geodesic.mathdoc.fr/item/MV_1969_21_2_a1/}
}