Regarding the posts on the Neuhaus (The Art of Piano Playing), with which I completely agree, I'd like to suggest another book that should be in everyone's library.

"The Literature of The Piano" by Ernest hutcheson. (Apologies, I have no capital h!!)

My edition, published by Knopf in 1972 is revised by Rudolph Ganz.

It is a Bible. Period. Geared towards "the amateur and student" in 450 pages it is a simply remarkable overview of the Western tradition from before Bach to the later 20th century. Absolutely brimming with musical examples, criticisms and suggestions, it has been one of my favourite books for decades. Whilst you might not always agree with the comments (all pianists do differ after all) you cannot help but be in awe of the scholarship behind the writing. Not only authoritative, but written in a kind and conversational manner, this book speaks to me like the perfect teacher. A lifetime wouldn't be enough for me to absorb everything within these pages.

With the Neuhaus, this book, and the quite remarkable "Music for the Piano" by Friskin and Freundlich, this trio of books represents the core of any pianist's library (of course, in my humble opinion)

Reading some of the comments on obtaining the Neuhaus, and this book and others, might I suggest "Abebooks". It is a world-wide data base with participating booksellers everywhere, advertising 110.000.000 books for sale. At the moment for example there are a couple of dozen editions of the Neuhaus for sale...