Gaya APA

Cetron, M, ., O'Toole, T. (1982). Encounters future : forecast of life into 21st the century . New York: McGraw-Hill.

Gaya MLA

Cetron, Marvin, ., O'Toole, Thomas. "Encounters future : forecast of life into 21st the century". New York: McGraw-Hill, 1982. Text.