Cameron, Robert, Land Snails in the British Isles (Preston Montford, 2003). The best aid to identifying land snails. Good illustrations by Gordon Riley and easy to use keys. Obtained from the Field Studies Council (www.field-studies-council.org)
Graham, Alistair, British Prosobranch and other Operculate Gastropod Molluscs, Keys and Notes for the Identification of the Species (London and New York, 1971). Includes all marine, freshwater and land based families.
Kerney, M. P., and R.A.D. Cameron, A Field Guide to the Land Snails of Britain and North-west Europe (London, 1979). Does include slugs. Coloured illustrations.
Macan, T. T., A Key to the British Fresh- and Brackish-Water Gastropods (Ambleside, 1969). Unfortunately out of print but second-hand copies are circulating along with photocopies of the original keys.
Pfleger, Vaclav, A Field Guide in Colour to Molluscs (Prague, 1998). Again, not easy to find.
Barker, G. M., The Biology of Terrestrial Molluscs (Wallingford, 2001). For the specialist, but reasonably up to date.
Chase, Ronald, Behavior and its Neural Control in Gastropod Molluscs (New York, 2002). Again for the specialist, but readable for those without too much scientific knowledge.
Ellis, A. E., British Snails (Oxford, 1926). An old book now but the main reference book on land snails in its time.
Hayward, Peter J., A Natural History of the Seashore, The New Naturalist Library (London, 2004).. A good section on sea shore snails.
Morton, J. E., Molluscs (London, 1967). Still the best overall introduction. Available second-hand.
Solem, Alan, The Shell Makers: Introducing Mollusks (New York, 1974). Out of print but again a good general introduction.
Dance, S. Peter, A History of Shell Collecting (Leiden, 1986)
Peter Dance has written the seminal work, itself a revision of an earlier book, Shell Collecting: An Illustrated History (London, 1966). Both are available second-hand.
—, Shells: Eyewitness Handbooks (London, 1992)
Jones, Barbara, Follies and Grottoes (London, 1953).
Thomas, Ingrid, The Shell: A World of Decoration and Ornament (London, 2007).
Tucker Abbott, R., and S. Peter Dance, Compendium of Seashells: A Colour Guide (Cajon, ca, 2000)
Wye, Kenneth R., The Encyclopedia of Shells (New York, 1998)