APA (7th ed.) Citation

Twenty... & Hester...[et.al.], J. (2002). 21 st Century Astronomy. W.W.Norton & Company,Inc.

Chicago Style (17th ed.) Citation

Twenty... and Jeff Hester...[et.al.]. 21 St Century Astronomy. W.W.Norton & Company,Inc, 2002.

MLA (8th ed.) Citation

Twenty... and Jeff Hester...[et.al.]. 21 St Century Astronomy. W.W.Norton & Company,Inc, 2002.

Warning: These citations may not always be 100% accurate.