12. Works Cited "Grand Canyon of Yellowstone National Park - AllYellowstonePark.com." Yellowstone National Park Vacations, Lodging, Old Faithful - AllYellowstonePark.com . N.p., n.d. Web. 1 Oct. 2011. <http://www.yellowstoneparknet.com/canyon_vill age/grand_canyon.php>. "The Grand Canyon of the Yellowstone Tours." Yellowstone Online Tours . N.p., n.d. Web. 1 Oct. 2011. <mms.nps.gov/yell/features/canyontour/index.htm >. "Yellowstone National Park (U.S. National Park Service)." U.S. National Park Service - Experience Your America . N.p., n.d. Web. 1 Oct. 2011. <http://www.nps.gov/yell/index.htm>.