%0 Journal Article %A J. Zabczyk %T Optimal control by means switchings %J Studia Mathematica %D 1973 %P 161-171 %V 45 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/sm-45-2-161-171/ %R 10.4064/sm-45-2-161-171 %G en %F 10_4064_sm_45_2_161_171