edited by Chester W. Harris
University of Wisconcin Press , 1967
Buku Teks
Guilford, J. P. (Joy Paul), 1897-1987, author
McGraw-Hill, 1987
Buku Teks
Edwards, Allen L.
Appleton Century Crofts, 1957
Buku Teks
Berdie, Douglas, author
The Scarecrow Press, 1974
Buku Teks
Busonowiwoho Sumotirto
Madjelis Ilmu Pengetahuan Indonesia, 1959
Buku Teks