@article{MS2_1967__20_165997,
     author = {G. Gr\"atzer and G.H. Wenzel},
     title = {On the {Concept} of {Congruence} {Relation} in {Partial} {Algebras.}},
     journal = {Mathematica Scandinavica},
     pages = {275--280},
     publisher = {mathdoc},
     volume = {20},
     year = {1967},
     zbl = {0175.28801},
     url = {http://geodesic.mathdoc.fr/item/MS2_1967__20_165997/}
}