Runners Connect: Treadmill vs Running Outside, http://runnersconnect.net/running-training-articles/treadmill-vs-running-outside/
Running Planet: Treadmill Training Versus Outside Running, http://www.runningplanet.com/training/treadmill-versus-outside-running.html
Runners World: Training in the Heat, http://www.runnersworld.com/race-training/training-heat
San Diego State: Moderating Effects of the Climatic Environment, http://coachsci.sdsu.edu/csa/vol36/rushall1.htm
Over 40 Runner: Running in te Heat and Humidity, http://www.over40runner.com/info/RunningInTheHeat.html
Clinical Journal of sports Medicine: Effect of Environmental Temperature on Shock Absorption Properties of Running Shoes, http://www.ncbi.nlm.nih.gov/pubmed/15867561