Birch, David, 1950-
Macmillan, 1991
Buku Teks
Geuss, Raymond, author
Cambridge University Press, 1999
Buku Teks
Hegeland, Hugo, author
Elanders Boktryckeri Aktiebolag, 1951
Buku Teks
Bowie, Andrew, author
Routledge , 1997
Buku Teks
Heap, Shaun P. Hargreaves
Routledge, 1995
Buku Teks