Nickersen, Jane Soames
The Devin-Adair Company, 1961
Buku Teks
Sinnigen, William G.
Macmillan, 1981
Buku Teks
Russel, Bertrand, author
Routledge, 1948
Buku Teks
Hall, H. R.
London: Methuen, [1924]
Buku Teks
edited by Paul Brand, Joshua Getzler
Cambridge University Press, 2012
Buku Teks