boiler part van book

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Hi everyone, I know this is a random question, but I'm wondering if anyone on here knows of a boiler part van book that's available to keep by my side when called out to repairs. I've seen another engineer with a book with diagrams and part numbers for numerous boilers, I just wish I'd asked him which book he had. Does anybody know of one. I've looked on mason, eBay and searched the net.

Thanks