What do you do when you need to clear the copyright of a song and find that it is held by the Highly Unlikely Song Co who, surprisingly, are not listed in Yellow Pages? Or when, a day before you start your three month tour of the Scottish Highlands, someone nicks all your PA, and you need to hire some instantly?

If you are like me you'll go to the pub, but the more organised members of the music world will instantly turn to their music yearbook and look up the relevant information. The yearbook will cover record companies, publishers, studios, instruments, marketing services, agents and PR companies, radio stations and so on. A couple of phone calls and the problem is solved.

That at least is the theory. The reality is that there are four music yearbooks on the market, each covering a slightly different area - weak in some places, strong elsewhere. And what's the betting that the one you've got doesn't cover the fix you currently find yourself in?

Radio and Record News produce their volume in August — which makes it reliable up to about the previous March. The price is cheeky — £3 for 42 pages of information and 24 pages of ads — but the coverage is good, especially for distribution and management.

Of its rivals, Music Week Yearbook is the cheapest, also at £3, although with double the number of pages and a very good section on studios, which R&RN completely omits. Kemps Music and Recording Industry Yearbook is much bigger, selling at £5.50 and including an excellent international section. However it's very weak on record companies, and if you are really into knowing where each record co is you'll want Music Master, published by John Humphries. It's not a yearbook but a record catalogue, but to get their list of over 300 addresses (undated monthly) you have to buy the whole catalogue — cost £30.

Lastly there's the British Record and Tape Directory, which at £7.46 (or just under 6p a page) simply isn't worth the effort, unless you require seating plans of the major British rock concert venues, which it alone carries.

Of course if you can't decide which to get you could always ask you local public reference library to get one of each - they usually oblige. But if you do get your PA gear stolen you'll need Kemps. They list insurance companies too.

Radio and Record News Yearbook is published by Needletime Music, (Contact Details); Music Week Yearbook by Music Week Ltd, (Contact Details); Kemps by the Kemps Group, (Contact Details), British Record and Tape Directory Parkway Publications Ltd, (Contact Details); Music Master by John Humphries, (Contact Details).