best books for home game player?

i've been playing NL hold 'em in a weekly home game for about a year. we play $0.50/$1.00 NL cash games or $30 freezeout tournies. i keep track of my wins/losses and since jan i'm about $700 up. i know factoring an hourly rate thats pretty weak but as long as i'm not losing i'm happy since its just for fun but of course i'd like to improve. so, what are the best books for low stakes NL hold 'em?