Deller, Ruth A., author
Emerald Publishing Limited, 2019
eBooks
Hazel, John, author
Routledge, 2000
Buku Teks
Hazel, John, author
Routledge, 2000
Buku Referensi
editor, John R. Hinnells
Macmillan, 1993
Buku Referensi
Garland, John K., author
Macmillan, 1975
Buku Teks