%0 Journal Article %A M. Kenku %T Atkin-Lehner involutions and class number residuality %J Acta Arithmetica %D 1977 %P 1-9 %V 33 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/aa-33-1-1-9/ %R 10.4064/aa-33-1-1-9 %G en %F 10_4064_aa_33_1_1_9