This is the perfect time of year to settle into your easy chair with a good aviation book. Two of my favorites are Rod Machado’s Private Pilot Handbook and Instrument Pilot’s Handbook. If you are working on either rating, I don’t think you will find better guides. I used the private pilot manual all through my primary training. It was the second reference (after my CFI of course) I would turn to to answer any questions I had. They are not only excellent study material for the written and oral exams, they are also handy manuals to have on hand throughout your training and flying career. Both have a central place in my aviation library and I highly recommend them.