Gaya APA

Service, P, E., Contra, I, A, O, D. (1978). Lessons in rotary drilling. unit V lesson 7. helicopter safety and survival procedures. (1978). : Texas: Petroleum Extension Service, (PETEX).

Gaya MLA

Service, Petroleum, Extension., Contra, Inter., Ass., Of, Drilling. "Lessons in rotary drilling. unit V lesson 7. helicopter safety and survival procedures.". 1978 : Texas: Petroleum Extension Service, (PETEX), 1978. Text.