Robson, Colin, author
Oxford, 2002
Buku Teks
Irvington Publ., 1967
Buku Teks
Harsja W. Bachtiar, 1934-, author
Indonesian Institute of Sciences, 1976
Buku Referensi
Strauss, Anselm L., author
Cambrigde University Press, 1987
Buku Teks
Hanushek, Eric A., author
Academic Press, 1977
Buku Teks