Disappearing polar bears and permafrost : is a global warming tipping point embedded in the ice? : hearing before the Subcommittee on Investigations and Oversight of the Committee on Science and Technology, House of Representatives, One Hundred Tenth Congress, first session, October 17, 2007.
Washington : U.S. G.P.O. : For sale by the Supt. of Docs., U.S. G.P.O., 2008.