@article{MV_1976_28_2_a35,
     author = {D. N. Krgovi\'c},
     title = {On intra-regular semigroups},
     journal = {Matemati\v{c}ki vesnik},
     pages = {405 },
     year = {1976},
     volume = {28},
     number = {2},
     url = {http://geodesic.mathdoc.fr/item/MV_1976_28_2_a35/}
}