The Power of Reading by Stephen D. Krashen is a very through book. I first got interested in reading books about books when I read Book Lust by Nancy Pearl, which by the way is worth having a copy. I can’t recommend Book Lust enough! But, back to The Power of Reading.
This has tons of citations from studies conducted in the 1990s and 2000s. Because there are no recent studies the book is a little dated in its citations. The copy I read was published in 2004, but the book was first published in 1993 and it seems not a lot of the references have been kept as up-to-date as a reader like me would have liked.
This book reads like a research paper so be prepared for that. If you want something that is a little easier to read I would highly suggest you read The Read-Aloud Handbook by Jim Trelease. His book is mentioned in any good study of reading books and the positive effects.
I gave The Power of Reading 3 out of 5 stars. Not great, but if you are doing a paper on the importance of reading or reading to improve english as a second language (ESL) then this is the book you need to check-out, but I wouldn’t recommend buying it.