Pan, I. L. (1997). Napocor, Spex-oxy firm up natural gas accord. Manila Times.
芝加哥风格引文Pan, Isabel L. "Napocor, Spex-oxy Firm Up Natural Gas Accord." Manila Times 1997.
MLA引文Pan, Isabel L. "Napocor, Spex-oxy Firm Up Natural Gas Accord." Manila Times, 1997.
警告：这些引文格式不一定是100％准确.