By Advanced Physics Project for Independent Learning
By Briggs, Raymond
By Vorderman, Carol
By United Nations Environment Programme
By Bob Digby, Becky Priest, Becky Tudor, Andy Slater, David Holmes
By Grant, Michael
By Lawrence James Campbell, R.J. Carlton
By Muirden James
By Ignotofsky, Rachel
By Andrew Solway
By Branwen Thomas
By Chris Ryan, Ryan, Chris
By Roger Priddy
By Williams, David J.
By Muriel Mandell, Frances Zweifel
By Beckett, B. S., B. S. Beckett
By BBC
By Adrian Forsyth, Laurel Aziz
By Cath Senker
By Steve Tomecek, National Geographic Kids
By Throp, Claire
By Colin Hynson
By Unknown, Heather Amery, Stephen Cartwright
By Romano Young, Karen, Collins Big Cat, Moon, Cliff
By Richards, Jean, Hariton, Anca
By Carole Telford
By Rob Alcraft
By Tom Jackson
By Penny Clarke, Mark Bergin