Below is a list of some excellent books for your iPad. I have curated this list over the last couple of months and I kept adding to it every time I stumble upon a resource somewhere online.I don't know if you like reading books on your iPad or not but let me tell you this: having at least a couple of titles installed on your iPad would really be of great help particularly in those moments when you are stuck somewhere and have nothing to do but waiting. Reading is a habit ( luckily a good one ) that we can ACQUIRE by force of habituation at least in the eyes of Skinnerian theory.The more you read , the fluent you get at reading and the more used your mind becomes to the act of reading.
Check out these books I selected for you. All of them are free and require iBooks. Enjoy