Here’s a few real live testimonials taken from Amazon and Ebay:
Amazon.in 5 star **** Amazing Chords
Plenty of Apps are available for keyboard chords!
But if you are looking for printed version of all the possible keyboard / Piano chords combination then I can recommend this book for you.
Amazon.com 5 star ***** Five Stars
Amazon.co.uk 5 star ***** Book
This is a book. It has printed therein explanations and diagrams of piano chords. The print is clear and the book is readable.