Nowadays most of the material I am actually using is online - that is the only way to get the primary material. Many of the real books - apart from the perennialy re-readable - are now redundant since I have extracted what little I want from them but I don't have the heart to part with them, particularly those volumes which are in poor condition and wouldn't be accepted by a 2nd-hand shop. If I ever manage to move I shall have to harden my heart a bit!