@article{MS2_1960__8_165756,
     author = {Folke Eriksson},
     title = {The {Relation} {Between} {Two} {Generalisations} of the {Notion} },
     journal = {Mathematica Scandinavica},
     pages = {339--355},
     year = {1960},
     volume = {8},
     zbl = {0106.36404},
     url = {http://geodesic.mathdoc.fr/item/MS2_1960__8_165756/}
}