O'Farrell, F. (1987). Is there a history of to be? Gregorianum, 68(3/4), 671-703.
芝加哥风格引文O'Farrell, Frank. "Is There a History of to Be?" Gregorianum 68, no. 3/4 (1987): 671-703.
MLA引文O'Farrell, Frank. "Is There a History of to Be?" Gregorianum, vol. 68, no. 3/4, 1987, pp. 671-703.
警告：这些引文格式不一定是100％准确.