Freedman, R. A. (2005). Universe. New York: W. H. Freeman and Company.
Chicago Style aipamenaFreedman, Roger A. Universe. New York: W. H. Freeman and Company, 2005.
MLA aipamenaFreedman, Roger A. Universe. New York: W. H. Freeman and Company, 2005.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.