KAZAN, TATARSTAN / RUSSIA - AUGUST 23 2017: Closeup of a serious master conducts initial instructions to employees in a uniform at a petroleum enterprise workshop on August 23 in Kazan

Editorial Use Only: This image can only be used for editorial purpose. Use of this image in advertising, commercial or for promotional purposes is prohibited unless additional clearances are secured by the licensee. 123RF.com does not provide any clearance services.