%0 Journal Article
%A Joachim A. Hempel
%T A pseudo-trigonometry related to Ptolemy's theorem
 and the hyperbolic geometry of punctured spheres
%J Annales Polonici Mathematici
%D 2004
%P 147-167
%V 84
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/articles/10.4064/ap84-2-5/
%R 10.4064/ap84-2-5
%G en
%F 10_4064_ap84_2_5