Vogt, William
William Sloane Associates, Inc., 1948
Buku Klasik
Moran, Emilio F, author
John Wiley & Sons, Incorporated, 2017
Buku Teks
Missenard, Andre, author
Hawthorn Books, 1957
Buku Teks
Ewert, Alan W., 1949-, author.
CABI, 2014
Buku Teks
Huntington, Ellsworth, author
John Wiley & Sons, 1945
Buku Teks