Ritchie, D. M.; Thompson, K. The UNIX Time-Sharing System(PDF). Communications of the ACM. 1974, 17 (7): 365–375 [2020-03-09]. (原始内容(PDF)存档于2015-06-11).
Ritchie, D. M.; Thompson, K. The UNIX Time-Sharing System(PDF). Communications of the ACM. 1974, 17 (7): 365–375 [2020-03-09]. (原始内容(PDF)存档于2015-06-11).