@article{MZ_1960__73_169833,
     author = {Edward S. O'Keefe},
     title = {On the independence of primal algebras.},
     journal = {Mathematische Zeitschrift},
     pages = {79--94},
     year = {1960},
     volume = {73},
     zbl = {0099.25901},
     url = {http://geodesic.mathdoc.fr/item/MZ_1960__73_169833/}
}