Free doesn't always mean good though. I recommend reading things that are rated well and reviewed properly by a community. I think that would be the most optimi

Free doesn't always mean good though. I recommend reading things that are rated well and reviewed properly by a community. I think that would be the most optimized way so you won't spend time reading books that don't explain things very well. You can always try other books if the one you're reading isn't explaining some parts very well though.