By Maurice Tucker
By Webster, Robert
By Mann, Stephen
By Winter, John D.
By Brian Simpson
By Vernon, Ron H.
By Brindley, G. W., Brown, G. C.
By Maurice E. Tucker
By Nriagu, Jerome O., Nieboer, Evert
By Dr J. Kourimsky
By Atwood, Fred
By Smith, Herbert Gladstone, Wells, Maurice Kingsley
By Adams, A.E., Mackenzie, W.S., Guilford, C.
By Best, Myron G.
By Schluter, Thomas, Trauth, Martin H.
By Paul Steinhardt
By Ian Mercer, G. Cressey (Researcher in Mineral Sciences, The Natural History Museum, London)
By Natural History Museum
By Andrew Ross
By Ronald Bonewitz
By Walter Schumann
By Arthur J. Whiteman
By Ailsa Allaby, Michael Allaby
By Roger Mason
By A. R. Ubbelohde
By Siegfried Siegesmund, Rolf Snethlage
By Edward S. Dana