The Japan Institute for Labour Policy and Training, 2006
Buku Teks
The Japan Institute for Labour Policy and Training, 2009
Buku Teks
Forbis, William H.
Charles E.Tuttle, 1981
Buku Teks
Freeman, Richard B.
Prentice-Hall, 1972
Buku Teks
United Nations Childrens Fund, 1984
Buku Teks