Conference proceedings : International round-table on Extreme space weather: Geomagnetic storms, GNSS disruptions and the impact on vital functions in society, Stockholm, 5-6 september 2012 Myndigheten för samhällsskydd och beredskap (MSB) 2012 Öppna dokument
Aircraft accident report : Uncontrolled descent and collision with terrain United Airlines flight 585, Boeing 737-200, N999UA 4 miles south of Colorado Springs municipal airport National Transportation Safety Board (NTSB) 2001 Öppna dokument