Carr-Saunders, A.M.
Clarendon Press, 1933
Buku Teks
Artikel Jurnal
Elliott, Philip
Herder and Herder, 1972
Buku Teks SO
Richards, J.M.
Newton Abbot: Davis and Charles, 1974
Buku Teks
Klostermaier, Klaus K.
Oneworld, [Date of publication not identified]
Buku Teks SO