APA引文
Krugman, P. R. International Economics, 12/e. Pearson.
芝加哥风格引文
Krugman, Paul R. International Economics, 12/e. Pearson.
MLA引文
Krugman, Paul R. International Economics, 12/e. Pearson.
警告：这些引文格式不一定是100％准确.