Gould, William B., IV
MIT Press, 1982
Buku Teks
Committee Reports, 1974
Buku Teks
edited by John O. Haley
Kendall / Hunt, 1988
Buku Teks
Ministry of Labor, 1953
Buku Teks
The Japan Institute for Labour Policy and Training, 2018
Majalah, Jurnal, Buletin