Oceana Publications, 1987
Buku Teks
Lazarus, Harold
Philosophical Library, 1957
Buku Teks
Larson, Harold J.
John Wiley & Sons, 1975
Buku Teks
Lange, Norbert Adolph, author
McGraw-Hill, 1967
Buku Referensi
edited by Charles A. Moser
Cambridge University Press, 1992
Buku Teks