By Prof Keith Smith (University of Stirling, UK), keith smith
By John Pickford
By Megson, T. H. G
By Schon, Donald A.
By Harper, Denis R.
By Forster, George
By Randall McMullan
By Gabriela Kutting
By Christian Ludwig, Stefanie Hellweg, Samuel Stucki
By Emma Marris
By Professor of Anthropology Brian Fagan (University of California USA)
By Matthew Alan Cahn, Rory O'Brien (Cleveland State University, USA (Emeritus))
By Vaclav Smil (Distinguished Professor Emeritus, University of Manitoba)
By David Elliott
By D.A. Fuchs
By Wyn P. Grant, Anthony Perl, Peter Knoepfel
By Theodore Goldfarb (SUNY, Stony Brook, USA)
By Terry L. Anderson, Donald R. Leal
By United Nations WWAP
By John Foster (Lancaster University, UK)
By Lynton Keith Caldwell
By J. van Tatenhove, B. Arts, P. Leroy
By Olive Heffernan
By D. Briggs, F. Courtney
By Michael Mason
By Timothy Doyle, Doug McEachern
By H.P. Rossmanith
By Ingemar Cox (Professor, university college, London, U.K.), Matthew Miller (NEC, Princeton, NJ, U.S.A.), Jeffrey Bloom (Thomson, Mathew Miller
By Robert T. Watson (Intergovernmental Panel on Climate Change)
By Nick Middleton