Roxas, P. (2003). P20-B road project to link ecozones in Central Luzon. Manila Times.
Chicago Style aipamenaRoxas, Patrick. "P20-B Road Project to Link Ecozones in Central Luzon." Manila Times 2003.
MLA aipamenaRoxas, Patrick. "P20-B Road Project to Link Ecozones in Central Luzon." Manila Times, 2003.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.