My recommendation for any medical student on an EM rotation would be a copy of "Pocket Emergency Medicine" by Richard D. Zane and Ron M. Walls. Like it's more popular sibling, "Pocket Medicine", it also comes as a small 3 ring binder (but with a black cover as opposed to blue). It'll probably cost you around $30 or so and while not a textbook geared towards learning, it is extremely handy as a pocket reference. The difference between it and other pocket references I've seen is that it is organized by chief complaint as opposed to problem or system. It is most useful to a student still honing his/her capacity to develop the sort of dual working DDx lists that EM often requires, the list of those things that are most likely and the ROWCS (Rule Out Worst-Case Scenario) list. It is of it's greatest utility if you take a peek at the nursing triage note, glean a CC, and take a glance at the CC in the book for 2 minutes so you have a starting point for both of the above DDx lists and therefore remember what relevant questions to ask and what parts of the physical exam to focus on. Then when you come out of the room and have pared down your respective DDx lists, take a peek at the book again and it can serve to demonstrate a good starting point for your initial work-up. After a while, you'll find this process ingrained and be relying on the book less and less, but as you are first learning to develop this skill on your own, it can be an invaluable reference. Good luck on your rotation.
