@article{MS2_1960__8_165741,
     author = {B. Jonsson},
     title = {Homogeneous {Universal} {Relational} {Systems.}},
     journal = {Mathematica Scandinavica},
     pages = {137--142},
     year = {1960},
     volume = {8},
     zbl = {0173.00505},
     url = {http://geodesic.mathdoc.fr/item/MS2_1960__8_165741/}
}