Ke Yan (Ke, Yan), Science and Technology in China, German Edition (Beijing 2005), p.109 Passages readable online
doi.org
dx.doi.org
Wu, Hequan (2002년 8월 6일), “The progress of communication technology subject of hi-tech research development plan of China”, 《International Conference on Communication Technology Proceedings, 2000》 (Beijing) 1: 3–4, doi:10.1109/ICCT.2000.889157, ISBN0-7803-6394-9