@article{RSMUP_1982__66__43_0,
     author = {Be\v{c}v\'a\v{r}, Jind\v{r}ich},
     title = {A generalization of a theorem of {F.} {Richman} and {C.} {P.} {Walker}},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {43--55},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {66},
     year = {1982},
     mrnumber = {664570},
     zbl = {0481.20034},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_1982__66__43_0/}
}