If you can spare the money, either Skyscape's 5 Minute Emergency Consult or Pepid for Emergency Medicine for your handheld (assuming you have one). This advice is for Quinn as well. I carry absolutely zero paper references with me now, and have since my senior year in residency. 5MEC is easier to use, as the format (and the font) is quicker and easier to get around. Pepid seems to have a greater breadth of content, but in the areas that 5MEC covers, it covers it pretty well. Obviously you don't expect Rosen's level of detail, but you don't want that much info most of the time anyway.