I purchased a copy of the EMS Field Guide from Informed guides.

http://store.informedguides.com/medical/ems-field-guider-bls-versiontm.html

I find it to be quite detailed and concise. Also, the pages are waterproof (Tyvek maybe?) and allow you to make notations with a sharpie that can be wiped off later.

Have been waiting for the backlog to clear from the Canada Post strike before ordering the Pet Emergency and NIMS field guides.
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They will swing back to the belief that they can make people...better. And I do not hold to that. So no more runnin'. I aim to misbehave.