@article{SMJ2_2000_26_2_a5,
     author = {Iliev, Valentin},
     title = {On a {New} {Approach} to {Williamson's} {Generalization} of {P\'olya's} {Enumeration} {Theorem}},
     journal = {Serdica Mathematical Journal},
     pages = {155--166},
     publisher = {mathdoc},
     volume = {26},
     number = {2},
     year = {2000},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SMJ2_2000_26_2_a5/}
}