Maher, Robert F.
University of Winconsin Press, 1961
Buku Teks SO
Hickman, Craig R.
New American Library, 1984
Buku Teks
Archiworld, [Date of publication not identified]
Buku Referensi
Mitchell, Ferd H.
CRC Press, 2016
Buku Teks
Schoorl, Johan Willem, 1927-
KITLV Press, 1993
Buku Teks SO