Gooch, R.K. (Robert Kent), 1893-1982, author
D. Van Nostrad, 1937
Buku Teks
Laski, Harold J., author
George Allen and Unwin, 1952
Buku Teks
Green, John Richard
New York The Co-operative Publication Society [t.th.]
Buku Teks
Rose, Richard, 1933-, author
Scott, Foreman, 1989
Buku Teks
Cash, Allen J., author
The Automobile Association, 1987
Buku Referensi