For those who know English and love the piano, I would suggest purchasing this wonderful manual, also available in its 2nd edition.
The cost is around 20 euros. I purchased it from amazon.com (used for 21 euros including shipping from the USA).
It is divided into extremely interesting topics for anyone who wants to deeply understand the piano in its entirety.
-One part is dedicated to instrument restoration (advice on how to manage the requalification of the soundboard, a keyboard, etc.)
-Another substantial part on the subject of "tuning".
-Analysis and requalification of the action.
The negative aspects of the book are essentially 2.
1) The images are in black and white, and often undersized, thus not facilitating the visibility of the subject.
2) The book proposes operations that are decidedly risky if not performed in the company of an expert.
http://books.google.de/books?id=IEJjQgAACAAJ&dq=arthur+reblitz&hl=it&sa=X&ei=7fzJUPXiE8vptQanmYHgBw&ved=0CDQQ6AEwAg