%0 Journal Article %A Rodrigo Arocena %T A refinement of the Helson-Szegö theorem and the determination of the extremal measures %J Studia Mathematica %D 1981 %P 203-221 %V 71 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/sm-71-2-203-221/ %R 10.4064/sm-71-2-203-221 %G en %F 10_4064_sm_71_2_203_221