%0 Journal Article
%A Olson, F.R.
%T An extension of a theorem of Nielsen
%J Portugaliae mathematica
%D 1966
%P 63-66
%V 25
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/PORMA_1966__25_2_114976/
%G en
%F PORMA_1966__25_2_114976