%0 Journal Article %A Ayuso, P. Fortuny %T Derivations and Valuation Rings %J Canadian mathematical bulletin %D 2013 %P 31-38 %V 56 %N 1 %U http://geodesic.mathdoc.fr/articles/10.4153/CMB-2011-128-6/ %R 10.4153/CMB-2011-128-6 %F 10_4153_CMB_2011_128_6