Having taken a neurophysiology course and a fan of Gary Matthew's Cellular Physiology of Nerve and Muscle I haven't really found a lot of good sources that describe the true origins of the resting potential. I find a lot just saying that it's due to the Na/K pumps, but nowhere other than my courses have I seen the discussion about electrochemical gradients - which is the foundation for the resting potential - nor talks about changes in the conductivity of certain ions which literally is the entire resting and action potentials.

I know that in many ways the true origins are a bit more difficult to understand, but I think there's even bigger problems oversimplifying the entire resting potential to a Na/K pump.