Ravelo, J. (1997). New program to boost crop yield, lower fertilizer costs. Manila Times.
芝加哥风格引文Ravelo, John. "New Program to Boost Crop Yield, Lower Fertilizer Costs." Manila Times 1997.
MLA引文Ravelo, John. "New Program to Boost Crop Yield, Lower Fertilizer Costs." Manila Times, 1997.
警告：这些引文格式不一定是100％准确.