April 20, 2013. Retrieved April 19, 2013. Cite news URL http://www.economist.com/news/special-report/21576219-carmakers-are-hedging-their-bets-powering-cars-great-powertrain-race Source title Propulsion systems The great powertrain race Carmakers are hedging their bets on powering cars Source date April 20, 2013 Name of publication [[The Economist]] URL access date April 19, 2013 Edition print