Tan, Kevin, Y.L., author
Lexis Nexis, 2010
Buku Teks
Laurel, Jose P., author
Lyceum Press, 1966
Buku Referensi
Schlesinger, Rudolf B.
The Foundation Press, 1950
Buku Klasik
Cambridge University Press, 2017
eBooks
Fox, James R., author
Oceana Publication, 1992
Buku Referensi