Philippines: The Summer Institute of Linguistics, 1954
Buku Teks
Elkins, Richard E., author
University of Hawaii Press, 1968
Buku Referensi
Andrea Malaya M. Ragragio, author
Nakanishi Printing Company, 2019
Artikel Jurnal
Tiamson, Alfredo T
Davao City Ateneo De Davao 1970
Buku Referensi
George, T.J.S
Oxford University Press, 1980
Buku Teks