Gaya APA

Blumenthal, J, H, -, D, B, -, G. (2007). 21st Century Astronomy (Cet.2). New York: Norton and company.

Gaya MLA

Blumenthal, Jeff, Hester, -, David, Burstein, -, George. "21st Century Astronomy". Cet.2 New York: Norton and company, 2007. Text.