Books
Asimov, Isaac."Total Collapse" How Did We Find Out About Black Holes?.New York: Walker Publishing Company, Inc., 1978, pp.49-51
Beasant, Pam. " The Stars" 1000 Facts About Space. New York:Times Four Publishing Ltd., 1992, pp.6-7
Couper, Heather and Henbest, Nigel. Black Holes. Ed. JackieWilson. New York: DK Publishing, Inc. 1996, pp.26-29
"Star" The World Book Encyclopedia .World Book, Inc.1990, pp.840
Images
"The space images used were created with support to Space TelescopeScience Institute, operated by the Association of Universities for Researchin Astronomy,Inc., from NASA contract NAS5-26555, and is reproduced withpermission from AURA/STScI." They are obtained royalty free.
Drawings
Drawing of a sandwich at Http://tqjunior:advanced.org/TEAM_4037,fromLaura Peters, March 1998.