For people who want to go a few stages further, Century Books thinks that it has provided the definitive text on Sinclair machines with its Century Computer Programming Course. What it has done is to publish a massive tome of text which is not indexed in any way. The book contains some interesting information on both machines but there is no way to find the information quickly. A proper index would, most probably, occupy another 10 pages.
While the expansion into the general sector of the market has been taking place, more Spectrum books have appeared. The state of play seems to be that anyone will do anything for a Spectrum.
The Century Computer Programming Course is written by Peter Morse, Ian Adamson, Ben Anrep and Brian Hancock. It costs £9.95 and is well worth the money.