Gaya APA

Zweng, C, A. (1969). The Instrument rating : a guide to the FAA written examination ; 20th revised (Ed. 20th. Revised). California: Pan American Navigation Service.

Gaya MLA

Zweng, Charles, Alfonso. "The Instrument rating : a guide to the FAA written examination ; 20th revised". Ed. 20th. Revised California: Pan American Navigation Service, 1969. Text.