Thaden, Edward C.
John Wiley & Sons, 1971
Buku Teks
Rogger, Hans, author
Longman, 1992
Buku Teks
Salisbury, Harrison E., author
Atheneum, 1965
Buku Teks
Lawrence, John
Farrar Straus & Cudahy, 1959
Buku Teks
Mitchell, Mairin, author
Sidgwick and Jackson, 1949
Buku Teks