I have just bought the following 3 books which are proving very useful for identification. Do any readers have any other favourites which they would recommend?
"The Timberland Press Guide to Succulent Plants of the World", by Fred Dortort,
"Succulents: The Illustrated Dictionary"
"Succulents II: The New Illustrated Dictionary",
both by Maurizio Sajeva & Mariangela Costanzo