@article{MV_1972_24_1_a46,
     author = {S. Lajos},
     title = {A characterization of semilattices of  left groups},
     journal = {Matemati\v{c}ki vesnik},
     pages = {363 },
     publisher = {mathdoc},
     volume = {24},
     number = {1},
     year = {1972},
     url = {http://geodesic.mathdoc.fr/item/MV_1972_24_1_a46/}
}