Barrett, O. W. (1928). The tropical crops. The Macmillan Company.
Cita Chicago (17th ed.)Barrett, Otis Warren. The Tropical Crops. New York: The Macmillan Company, 1928.
Cita MLA (9th ed.)Barrett, Otis Warren. The Tropical Crops. The Macmillan Company, 1928.
Atenció: Aquestes cites poden no estar 100% correctes.