@article{10_4064_cm_25_1_11_14,
     author = {J. P{\l}onka},
     title = {On the number of polynomials of a universal algebra, {IV}},
     journal = {Colloquium Mathematicum},
     pages = {11--14},
     publisher = {mathdoc},
     volume = {25},
     number = {1},
     year = {1972},
     doi = {10.4064/cm-25-1-11-14},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-25-1-11-14/}
}