agreed- Easy EMG for a pocket book is a good start
or EMG secrets, though the format can get a little tiring trying to read it. there are alot of good pearls in it though...
For a text: the classic Preston and Shapiro is very EASY to read and learn from.
Unfortunately the topic of EMG/NCS is beyond mneumonics you really need to understand it so you can trouble shoot while you are doing it...