@article{MV_1969_21_1_a2,
     author = {{\DJ}. Kurepa},
     title = {A remark on equivalence relation},
     journal = {Matemati\v{c}ki vesnik},
     pages = {27 },
     year = {1969},
     volume = {21},
     number = {1},
     url = {http://geodesic.mathdoc.fr/item/MV_1969_21_1_a2/}
}