Callan, Hilary
Oxford University Press , 1970
Buku Teks
edited by Patrick W. Colgan
John Wiley & Sons, 1978
Buku Teks
edited by Henrietta L. Moore
Routledge, 1996
Buku Teks
Tavistock publications, 1966
Buku Teks
edited by J.P.B. de Josselin de Jong
Koninklijk, 1984
Buku Teks