Katigbak, A. F. (2005). UP honors former energy secretary. Philippine Star.
Lua i Stíl Chicago (17ú heag.)Katigbak, Antonio F. "UP Honors Former Energy Secretary." Philippine Star 2005.
Lua MLA (9ú heag.)Katigbak, Antonio F. "UP Honors Former Energy Secretary." Philippine Star, 2005.
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