%0 Journal Article %A Hamilton, Nicholas %A Penttila, Tim %T Sets of type $(a,b)$ from subgroups of $\Gamma L (1, p^R)$ %J Journal of Algebraic Combinatorics %D 2001 %P 67-76 %V 13 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/item/JAC_2001__13_1_a2/ %G en %F JAC_2001__13_1_a2