1. CNN: Investigating the philadelphia Amtrak train derailment. http://www.nytimes.com/interactive/2015/05/13/us/investigating-the-philadelphia-amtrak-train-crash.html?_r=0 (2015)
2. CNN: Amtrak restores service after fatal crash; investigation continues. http://www.cnn.com/2016/04/03/us/philadelphia-amtrak-derailment/ (2016)
3. AAR: Interoperable Train Control Wayside Interface Unit Requirements Railway Electronics S9202 (2010)
4. AAR: Office to Locomotive ICD version draft 2.6 S 9352A (2010)
5. Joint Council on Transit Wireless Communications: Positive Train Control-White Paper (2012)