There are umpteen zillion piano books available in music stores and online at such places as Amazon. And piano books are usually necessary if your goal is to become a better pianist.
But how does a person know which piano books are necessary and which books are redundant, to say nothing of good or bad. There are books on music theory, scales, chords, books about composers, books about music in general, and of course piano lesson books by Schaum, Williams, Alfred d'Auberge, Bastien, John Thompson, Glover, etc., etc.
The best way is to divide the study of piano playing into it's components:
General lesson piano books:
While there are many, for the adult beginner I would select the series by Bastien titled "The Adult Beginner" It is excellent for adults, and includes quite a bit of music theory along with the piano lessons.
General books about music:
Far and away the most inspiring book about music in general is "The Joy of Music" by Leonard Bernstein. If you want to wrap your brain around music, this is the book for you. (Bernstein, in case you don't know, was both a great conductor and a great composer, having written "West Side Story" and many others.)
Another great selection would be "What To Listen For In Music" by Aaron Copeland. (He was also a great composer.)
Technique books:
The best book I have found for developing finger dexterity and piano technique is a book that has been around for a hundred years or so, but is still the standard. It is "The Virtuoso Pianist in 60 Exercises - Complete: Piano Technique" by C. L. Hanon
Music theory books:
There are many, most of which are complex and difficult to understand, but a good choice for a beginner would be "The Complete Idiot's Guide To Music Theory" by Michael Miller.
Books on piano chords:
In this category I'm going to have to cast all modesty aside and select my own book titled "Piano Chords & Chord Progressions: The Secret Backdoor To Exciting Piano Playing". It's thorough, cheap, and very easy to read and understand.
Song books:
In addition to books that teach all aspects of piano playing, you'll need several good songbooks so you can practice the things you are learning. The piano books you select are largely a matter of taste: if you love rock, you'll want to buy books of rock songs. If you love jazz, or gospel, or pop, or whatever, you'll want to get the song books appropriate to your likes and tastes.
But in addition to regular piano song books, be sure to also get a "fake book". A fake book is a book which contains the melody, the words, and the chord symbols for songs. Usually a fake book has a thousand or more songs in it, so it is a huge bargain.
When I was a teenager fake books were illegal, but they were sold under the counter to musicians all the time. I paid $50. for my first fake book (which I still have, incidentally) which contained only 200 songs. Fifty bucks back then is similar to the national debt now. But it was something working musicians had to have.
Now fake books contain thousands of songs and sell for much less -- often just $25. or so. So be sure to pick one up -- preferably several, as they come in all flavors -- jazz, folk, western, gospel, pop, and just about any other musical classification that you could think of.
All of these books can be obtained at your local music store or from online stores such as Amazon.
Then there is another totally different class of piano books that are part of an audio-visual course. Usually these books are supplementary to the DVD or CD (or both) which comprises the course. This type of piano books are new in the history of the world, because obviously DVDs and CDs haven't existed all that long. This type of course puts it all together, so in addition to reading a book, you can hear the instruction and see it being demonstrated on your own TV or computer screen.
To locate this type of piano book just type in a search query such as "piano lessons on DVD" or "piano instruction on DVD" or a similar phrase. There are many such courses now available through the internet, and more being born every day.
