Scheerer, Otto
Manila: Bureau of Printing, 1908
Buku Teks
Smith, J.N., author
Batavia: Nijhoff Albrecht, 1926
Buku Teks
Artikel Jurnal
Manila: National Library of Philippine, 1978 - 1984
Buku Referensi
Wyler, Alfred
Zurich : Pro Helvetia, Schweizer Kulturstiftung, 1984
Buku Teks