Foote, Robert L. <br/><br/>
An intrinsic formula for the cross ratio in spherical and hyperbolic geometries/ 
Robert L. Foote and Xidian Sun. 
 - Washington D. C.:  Mathematical Association of America,  ŠJul 2012-Sept 2015. 
 - v43 n3, pages 182--188:  Illustrations;  25 cm. 
<br/><br/><label>ISSN: </label>0746-8342 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geometry.
<br/><br/><label>Dewey Class. No.: </label>DPer 510.5 C697 Jan 2012-Sept 2015 v. 43 & 46, n. 1-4