Gaya APA
Zeilik, M, &, G, S, A. (1998).
Introductory Astronomy & Astrophysics (Fourth Edition).
Amerika:
Cengage Learning.
Gaya MLA
Zeilik, Michael, &, Gregory,, Stephen, A..
"Introductory Astronomy & Astrophysics".
Fourth Edition
Amerika:
Cengage Learning,
1998.
Printed Book.