@article{CMUC_1965__6_1_a4,
     author = {Drbohlav, Karel},
     title = {A categorical generalization of a theorem of {G.} {Birkhoff} on primitive classes of universal algebras},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {21--41},
     publisher = {mathdoc},
     volume = {06},
     number = {1},
     year = {1965},
     mrnumber = {0177926},
     zbl = {0128.02203},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1965__6_1_a4/}
}