Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia
Michael E. Mann*†, Zhihua Zhang*, Malcolm K. Hughes‡, Raymond S. Bradley§, Sonya K. Miller*, Scott Rutherford¶,
and Fenbiao Ni
‡
*Department of Meteorology and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802;
‡Laboratory of
Tree-Ring Research, University of Arizona, Tucson, AZ 85721;
§Department of Geosciences, University of Massachusetts, Amherst, MA 01003-9298;
and ¶Department of Environmental Science, Roger Williams University, Bristol, RI 02809
Communicated by Lonnie G. Thompson, Ohio State University, Columbus, OH, June 26, 2008 (received for review November 20, 2007)
http://www.pnas.org/content/105/36/13252.full.pdf#page=1&view=FitH

found from:

Hockey stick controversy
http://en.wikipedia.org/wiki/Hockey_stick_controversy