Sarah Ashwin, editor
Routledge, 2000
Buku Teks
Thompson, June M., author
Westview Press, 1990
Buku Teks
Mitchell, Mairin, author
Sidwick and Jackson, 1949
Buku Teks
Vernadsky, George
Yale University Press, 1954
Buku Teks
Mitchell, Mairin, author
Sidgwick and Jackson, 1949
Buku Teks