%0 Journal Article %A Chrastina, Jan %T On a theorem of J. Peetre %J Archivum mathematicum %D 1987 %P 71-75 %V 23 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/ARM_1987__23_2_a2/ %G en %F ARM_1987__23_2_a2