%0 Journal Article
%A Erdahl, R. M.
%A Ryshkov, S. S.
%T The Empty Sphere
%J Canadian journal of mathematics
%D 1987
%P 794-824
%V 39
%N 4
%U http://geodesic.mathdoc.fr/articles/10.4153/CJM-1987-039-7/
%R 10.4153/CJM-1987-039-7
%F 10_4153_CJM_1987_039_7