http://www.amazon.com/Tunnels-Chi-Harrowing-Underground-Battlefields/dp/0891418695/ref=sr_1_fkmr0_1?ie=UTF8&qid=1327755162&sr=8-1-fkmr0
Thans for the link. My brother was stationed in Cu Chi. He told about the tunnels found under their base. He also said some of the tunnels contained French weapons.