Christian, Brian; Markson, Tom; Skrenta, Rich (eds.). "Section 5.3". The PDP-11 How-To Book (Revision 1 ed.). Archived from the original on 2018-08-01. Retrieved 2018-08-01. (NB. Has a reference for the RT-11 operating system running on the PDP-11 minicomputer, which shows in section 5.3 that .COM is used to refer to a command file.)
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Christian, Brian; Markson, Tom; Skrenta, Rich (eds.). "Section 5.3". The PDP-11 How-To Book (Revision 1 ed.). Archived from the original on 2018-08-01. Retrieved 2018-08-01. (NB. Has a reference for the RT-11 operating system running on the PDP-11 minicomputer, which shows in section 5.3 that .COM is used to refer to a command file.)