Stewart, Hugh B.
Dow Jones-Irwin, 1989
Buku Teks
Lonnroth, Mans
Pergamon Press, 1980
Buku Teks
Hardy, Thomas, 1840-1928, author
Macmillan, 1985
Buku Teks
Persatuan Insinyur Indonesia or PII, 2018
Majalah, Jurnal, Buletin
National Association of Social of social Workers, 1980
Buku Teks