I'm happily working through William Tang's Spectrum Machine Language for the Absolute Beginner. I've already found one error (in the EZCODE listing), which I was able to fix myself, but to save myself further headaches, I would like to know if an errata document (official or otherwise) exists for this book. By Googling, I have found reference to the errata for a similar book (Mastering Machine Code on Your ZX Spectrum), but nothing for this particular book.
Couldn't find an errata either but you can download the code as a TZX file from World of Spectrum
You can either load that into an emulator and look at the code there (if you want to continue to type it in yourself...best way to learn!) or you can get WinTZX2TAP from World of Spectrum Utilities to convert it to a TAP then get the basic listing using Tappeto (also on WOS Utils).
One thing I noticed when I did all that was Tappeto shows a back-tick on line 130 (like the book listing) but when it's loaded into FUSE it appears as a UK pound sign (£). Not sure what that's about!
EDIT: Just found this on Wikipedia: The ZX Spectrum character set is the variant of ASCII used in the British Sinclair ZX Spectrum family computers. It is based on ASCII-1967 but the characters ^, ` and DEL are replaced with ↑, £ and ©.