https://www.vedomosti.ru/business/articles/2012/11/14/opek:-obem-spekulyativnyh-kontraktov-prevysil-fizicheskij-rynok-nefti?utm_source=telegram&utm_campaign=share&utm_medium=social&utm_content=opek%3A-obem-spekulyativnyh-kontraktov-prevysil-fizicheskij-rynok-nefti