1. China National Coal Group Corporation, Beijing, People’s Republic of China
2. Coal Branch, Zhongtian Hechuang Energy Co., Ltd, Ordos, People’s Republic of China
3. China Coal Energy Research Institute Co., Ltd, Xi'an, Shaanxi, People’s Republic of China
4. School of Mines, Key Laboratory of Deep Coal Resource Mining, Ministry of Education of China, China University of Mining and Technology, Xuzhou, People’s Republic of China