APA

Knowles J. B., . (1994). Direct Digital Control System. england: research studies press ltd.

Chicago

Knowles J B, . 1994. Direct Digital Control System. england: research studies press ltd.

Harvard

Knowles J. B., . (1994). Direct Digital Control System. england: research studies press ltd.

MLA

Knowles J B, . Direct Digital Control System. england: research studies press ltd. 1994.