Need help choosing books for learning to draw.

I have been drawing for a while now (not hardcore 5 hours a day practice but just when i got some free time). I am currently lacking on fundamentle skills and I find it hard to find good digital material on my level. I am currently choosing between drawing on the right side of the brain and figure drawing for all it's worth. I am mostly interrested in drawing people and not really objects. Are the fundamentle principles the same or are they different and what book would suit me the best?