Conkling, Edgar C.
McGraw-Hill, 1976
Buku Teks
Hackett, Brian
Percival marshall, 1950
Buku Teks
Huntley, James R.
NATO Information Service, 1972
Buku Teks
J.B. Lippincott Company, 1969
Buku Teks SO
Ashby, Eric
Stanford University Press, 1978
Buku Teks