%0 Journal Article %A Zoltán Buczolich %T Ergodic averages and free $ℤ^2$ actions %J Fundamenta Mathematicae %D 1999 %P 247-254 %V 160 %N 3 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/fm-160-3-247-254/ %R 10.4064/fm-160-3-247-254 %G en %F 10_4064_fm_160_3_247_254