1. Military specification – flight control systems – design installation and test of piloted aircraft, general specification for MIL-F-9490D;Anonymous,1975
2. Handling qualities requirements for military rotorcraft, aeronautical design standard, ADS-33-E-PRF;Anonymous,2000
3. Anonymous, MD helicopters model 369/500N/600N torque event/retirement index number explanation, MD Helicopters Service Letter, 15 May, 2001.
4. Bell 412EP product data;Anonymous,2002
5. Condition based maintenance plus DoD guidebook;Anonymous,2008