By Cecilia Fitzsimons
By Helen Edom, Moira Butterfield, Kate Davies
By Bown, D., Meadway, Wendy
By John Stringer
By Peppa Pig
By John B. Shoven (Stanford University, California), John Whalley (University of Western Ontario)
By Kym Anderson, Richard Blackhurst
By Clarke, Juliette Clarke
By Daniel Lord Smail
By David Wilkinson, Rev Rob Frost, Wilkinson, David A.; Frost, Rob
By Camilla de la Bedoyere
By Nicola Barber
By Paul McEvoy, Tracey Gibson
By Parker, Steve, Parr, David
By Edom, Helen, Abel, Simone
By Anna Claybourne
By Barbara Taylor Cork
By caroline pitcher, Jackie Morris
By Collins GCSE
By Sally Grindley
By University N Gregory Mankiw (Harvard University)
By Houghton, J.
By United Nations
By Una Jacobs
By Eleonore Schmid
By Tilda Kelly
By Michael White
By David H. Johnson, Frank P. Johnson