Spengler, Joseph J. (Joseph John), 1902-1991, author
Prentice-Hall, 1974
Buku Teks
Gandhi, M.K.
Ahmedabad Navajivan 1954
Buku Teks
Korean Society of welfare for the aged, {s.a}
Majalah, Jurnal, Buletin
Timms, Rita, author
Routledge, 1982
Buku Referensi
Gilbert, Neil, author
Allyn and Bacon, 1998
Buku Teks