By Hambrey, Michael
By Adams, A.E., Mackenzie, W.S., Guilford, C.
By Peters, K. E.
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 Ailsa Allaby, Michael Allaby
By A. R. Ubbelohde
By Edward S. Dana