Gaya APA
Bittner, R, H. (1982).
Fundamentals of Machine Operation Agricultural Machinery Safety .
Moline USA:
John Deere Service Pubications.
Gaya MLA
Bittner, Richard, H..
"Fundamentals of Machine Operation Agricultural Machinery Safety".
Moline USA:
John Deere Service Pubications,
1982.
Teksbook.