BEIJING, Sept. 19 (Xinhua) -- Chinese President Xi Jinping has called for carrying out in-depth study of the Yan'an spirit and vigorously promoting and carrying forward the spirit.

Xi, also general secretary of the Communist Party of China Central Committee and chairman of the Central Military Commission, made the remarks in a letter to congratulate the China Yan'an Spirit Research Society on the opening of its sixth congress in Beijing on Saturday and on its 30th founding anniversary.