Speyer, Edward, author
John Wiley & Sons, 1994
Buku Teks
Clark, Wilfrid E. Le Gros, author
Holt, Rinehart and Winston, 1967
Buku Teks
Moore, Ruth
Alfred A. Knoff, 1961
Buku Teks
Leet, Lewis Don, author
Dell, 1964
Buku Teks
Ingpen, Robert, author
Dragon's World, 1993
Buku Referensi