International Business Machines. (1987). Disk operating system (Version 3.30.). International Business Machines.
Citazione stile Chigago Style (17a edizione)International Business Machines. Disk Operating System. Version 3.30. Boca Raton, Fla: International Business Machines, 1987.
Citatione MLA (9a ed.)International Business Machines. Disk Operating System. Version 3.30. International Business Machines, 1987.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.