Greulach, Victor A., author
John Wiley & Sons, 1966
Buku Teks
Harrington, Harold David, author
Swallow Press, 1979
Buku Teks
Raven, Peter H., author
Worth Publisher, 1986
Buku Referensi
Holttum, R.E.
Authority , 1966
Buku Teks
Laetsch, Watson M., author
Little, Brown, 1979
Buku Teks