Gaya APA

Praat, L, N., Hartmann, W, K. (1990). The Cosmic Voyage: Through Time And Space (-). California: Wadsworth Publishing Company.

Gaya MLA

Praat, Lorraine, Nichols., Hartmann, William, K. "The Cosmic Voyage: Through Time And Space". - California: Wadsworth Publishing Company, 1990. Text.