Blackman, Tim, author
Routledge, 1995
Buku Teks
Hammersley, Martyn, author
Paul Chapman Publishing, 2002
Buku Teks
Adams, John, 1938-, author
Routledge & Kegan Paul, 1981
Buku Teks
Marett, Paul
Ashgate, 2002
Buku Teks
Ilbert, Courtenay
Oxford University Press , 1947
Buku Teks