https://www.leaprate.com/2016/07/cme-to-list-new-european-style-fx-option-contracts-in-place-of-american-style/
http://www.cmegroup.com/trading/fx/g10/euro-fx_contractSpecs_options.html?foi=O&optionProductId=8119&optionExpiration=8119-U6#optionProductId=8117
http://www.cmegroup.com/notices/ser/2016/07/SER-7688.pdf
http://www.investopedia.com/terms/o/over-the-countermarket.asp
http://www.cmegroup.com/confluence/display/EPICSANDBOX/Volatility-Quoted+Options
http://www.cmegroup.com/trading/cme-direct/files/cme-direct-for-the-trader.pdf
