@article{10_21136_CMJ_1974_101276,
     author = {Johnson, R. H.},
     title = {A new class of enumeration problems},
     journal = {Czechoslovak Mathematical Journal},
     pages = {573--583},
     publisher = {mathdoc},
     volume = {24},
     number = {4},
     year = {1974},
     doi = {10.21136/CMJ.1974.101276},
     mrnumber = {0357215},
     zbl = {0327.05113},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1974.101276/}
}