PLEASE. Do everyone a favor and write an Amazon review if you end up reading a book (or trying to and giving up in disgust). It does not have to be much. Just tell what you think of the book. By the way, many times I have found the 1 and 2 star reviews on self published works to be far more revealing about the book than the more stellar reviews.
From the top 100 free list
Off The Grid Hydroponics - No Power Needed
This book was written to explain the Kratky method of hydroponics. The Kratky method refers to growing plants in a nutrient solution as you would in hydroponics however you do not use an air stone and the roots are mostly submerged at all times in the solution. This method is possible with many different plants and works very well for growth.
[#98. An interesting idea. One 4 and one 5 star review.]
ETA: I took a look at it and gave this pamphlet sized work 4 stars.