"Downward Pressure on the Accident Rate" Nicholas A. Sabatini, Herndon, VA May 12, 2006 International Society of Air Safety Investigators [1] 16 Nisan 2014 tarihinde Wayback Machine sitesinde arşivlendi.(İngilizce)
"Downward Pressure on the Accident Rate" Nicholas A. Sabatini, Herndon, VA May 12, 2006 International Society of Air Safety Investigators [1] 16 Nisan 2014 tarihinde Wayback Machine sitesinde arşivlendi.(İngilizce)