1. Advisory Committee on the Future of the U.S. Space Program,1990
2. Daniel Saul Goldin, NASA Administrator, April 1, 1992–November 17, 2001,2009
3. Uselessness of Japan's human space exploration;Tachibana;Bungeishunju,2012
4. The barrier against manned space transport plan in Japan;Nakano,2015
5. Public Survey on Space Exploration,2015