Villanueva, M. A. (2001). Banker named energy chief / Marichu Villanueva and Donnabelle Gatcula. Philippine Star.
Lua i Stíl Chicago (17ú heag.)Villanueva, Marichu A. "Banker Named Energy Chief / Marichu Villanueva and Donnabelle Gatcula." Philippine Star 2001.
Lua MLA (9ú heag.)Villanueva, Marichu A. "Banker Named Energy Chief / Marichu Villanueva and Donnabelle Gatcula." Philippine Star, 2001.
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