It is good that you want to read and learn. Too many nurses I've seen are cocky and figure they know it all or will remember it all without writing anything down. A brilliant resident I work with takes notes every shift for things he did not know or wanted to increase his knowledge base about. He reviews the notes and researches at home and is stronger for the next shift.
Go to amazon and look up Emergency RN books, there are several good ones. Look for the highest rated ones. You will need to know why we give what we do for allergic reactions, MI, kidney stones, etc. Some of these books explain they physiological background and treatments for conditions we commonly see in the ED.
Also, I make notes in the note program of smart phone. I have notes on drips, unusual medication preparations, important things I've learned and want to store in my long-term memory (including some that resident taught me!).
Best of luck mate.