@article{AUCMP_1984__25_1_a8,
     author = {Smith, J. D. H.},
     title = {Two enumeration principles for free algebras},
     journal = {Acta Universitatis Carolinae. Mathematica et Physica},
     pages = {53--58},
     publisher = {mathdoc},
     volume = {25},
     number = {1},
     year = {1984},
     mrnumber = {0778076},
     zbl = {0547.08008},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUCMP_1984__25_1_a8/}
}