(2000). All A.O. 121 and 135 operators. Philippine Star.
Cita Chicago (17th ed.)"All A.O. 121 and 135 Operators." Philippine Star 2000.
Cita MLA (9th ed.)"All A.O. 121 and 135 Operators." Philippine Star, 2000.
Atenció: Aquestes cites poden no estar 100% correctes.