Critchfield, W. B. (1957). Geographic variation in Pinus Contorta. Harvard University.
芝加哥风格引文Critchfield, William Burke. Geographic Variation in Pinus Contorta. Cambridge, Mass.: Harvard University, 1957.
MLA引文Critchfield, William Burke. Geographic Variation in Pinus Contorta. Harvard University, 1957.
警告：这些引文格式不一定是100％准确.