◇ デイリーポータルZ:渋谷川の源流をさがす
http://portal.nifty.com/2006/06/16/a/
◇ Naoya Hatakeyama - River Series & Underground
http://www.berk-edu.com/RESEARCH/hatakeyama/index.htm
http://images.google.co.jp/images?svnum=10&hl=ja&lr=&q=naoya+hatakeyama+underground
http://www.a-i-t.net/news/003/hidaka_j.html