Alcala, A. (2008). Agusan River estuary development potential. Malaya.
Chicago Style (17. basım) AtıfAlcala, Angel. "Agusan River Estuary Development Potential." Malaya 2008.
MLA (9th ed.) AtıfAlcala, Angel. "Agusan River Estuary Development Potential." Malaya, 2008.
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