%0 Journal Article %A Klaška, Jiří %T Criteria for testing Wall's question %J Czechoslovak Mathematical Journal %D 2008 %P 1241-1246 %V 58 %N 4 %U http://geodesic.mathdoc.fr/item/CMJ_2008_58_4_a27/ %G en %F CMJ_2008_58_4_a27