PianoTuningHowTo highly recommends this book.  Many professional piano tuners have started with this book.

Piano Servicing, Tuning, and Rebuilding: For the Professional, the Student, and the Hobbyist

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Piano Servicing, Tuning, and Rebuilding: For the Professional, the Student, and the Hobbyist - Product Description

The second edition of this world famous book.

Piano Servicing, Tuning, and Rebuilding: For the Professional, the Student, and the Hobbyist - Details

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Piano Servicing, Tuning, and Rebuilding: For the Professional, the Student, and the Hobbyist 4.7 out of 5 based on 46 ratings. 552 user reviews
Piano Servicing, Tuning, and Rebuilding: For the Professional, the Student, and the Hobbyist The second edition of this world famous book. $29.95 http://ecx.images-amazon.com/images/I/51APKG6FJSL._SL160_.jpg
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