O'Farrell, F. (1987). Is there a history of to be? Gregorianum, 68(3/4), 671-703.
Chicago Style (17th ed.) CitationO'Farrell, Frank. "Is There a History of to Be?" Gregorianum 68, no. 3/4 (1987): 671-703.
MLA (8th ed.) CitationO'Farrell, Frank. "Is There a History of to Be?" Gregorianum, vol. 68, no. 3/4, 1987, pp. 671-703.
Warning: These citations may not always be 100% accurate.