Thanks for pointing out the contrasts (and the original article). I have battled this for a long time - there are classroom scenarios where there is only so muc

Thanks for pointing out the contrasts (and the original article). I have battled this for a long time - there are classroom scenarios where there is only so much you can ask, and when you get to self-study situations, it gets even harder. Can you tell me which book the second proof is from?