%0 Journal Article %A Henri Berestycki %A François Hamel %A Nikolai Nadirashvili %T The speed of propagation for KPP type problems. I: Periodic framework %J Journal of the European Mathematical Society %D 2005 %P 173-213 %V 7 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4171/jems/26/ %R 10.4171/jems/26 %F JEMS_2005_7_2_a1