i have five different ECG books and this one was the first one that helped me to understand these squiggly lines. i'm not a patient woman sometimes, but i haven't thrown this book at a wall yet so it's obviously useful with the basics.
Probably the best book I've recommended to my students. There are too many rhythms, Coronary Care I/II don't exactly teach you telemetry, but this will. Other tips they found useful were utilizing online continous strip quizzes and calipers, which I used only during examinations for the most part.