References
- IATA. (2015). Fuel price analysis. Retrieved July 21, 2015, from http://www.iata.org/publications/economics/fuel-monitor/Pages/price-analysis.aspx
- NASDAQ. (2015). Crude oil WTI (NYMEX) price. Retrieved July 21, 2015, from http://www.nasdaq.com/markets/crude-oil.aspx?timeframe=1y