Gaer, Joseph
Dodd, Mead, 1956
Buku Teks SO
Gar, Joseph
Dodd, Mead, 1963
Buku Teks SO
edited by Stewart Sutherland, Leslie Houlden, Peter Clarke, Friedhelm Hardy
Routledge, 1988
Buku Referensi
Ewing, J.H., editor
Dell Publishing, 1964
Buku Teks SO
edited by Peter Clarke
Routledge, 1988
Buku Teks SO