Something to refer to in a pinch. A nursing reference sidekick
Honestly, in a pinch we used our tablets/phones. Just made sure the source was legit.
If you want something more specific some books have apps you can download either with the purchase of the text or for a fee without the hard copy. I remember buying the Davis's drug guide app when I went into homecare shifts because I didn't want to be unprepared. Well, the drug guide was missing some of the meds but the drugs website had more info than I knew what to do with, as well as other sites found in a google search. Again, just make sure the site is legit.