为纪念六四 山东退休教授孙文广被关黑监狱43天 (Shandong retired professor Sun Wenguang was detained 43 days in black jail for commemorating June Fourth) Radio Free Asia, June 18, 2018 https://www.rfa.org/mandarin/yataibaodao/renquanfazhi/ql1-06182018101030.html