1. Football Helmet Drop Tests on Different Fields Using an Instrumented Hybrid III Head
David C. Viano, Chris Withnall, Michael Wonnacott
Annals of Biomedical Engineering  vol: 40  issue: 1  first page: 97  year: 2012  
doi: 10.1007/s10439-011-0377-3

2. Comparison of Speed and Agility Performance of College Football Players on Field Turf and Natural Grass
Graydon L Gains, Andy N Swedenhjelm, Jerry L Mayhew, H Michael Bird, Jeremy J Houser
Journal of Strength and Conditioning Research  vol: 24  issue: 10  first page: 2613  year: 2010  
doi: 10.1519/JSC.0b013e3181eccdf8