Artikel Jurnal
Wang, Yu-Chuan
The American Numismatic Society, 1951
Buku Teks
Hong Zheng, translator
Hunan People Publishing House, 2006
Buku Teks
Yang, C.K.
The Technology Press, 1959
Buku Teks
Leffingwell, William Henry
McGraw-Hill , 1950
Buku Teks