Wisconsin American Society of Agronomy , 1965
Buku Teks
Chen, Kuan I.
Bookman Associates, 1960
Buku Teks
Carr-Saunders, A.M.
Frank Cass, 1964
Buku Teks
Brown, Lester R.
W.W. Norton & Company, Inc., 1974
Buku Teks
Borrie, W.B.
Weidenfeld and Nicolson, 1970
Buku Teks