Pick up:
"The Art of Getting Over"- Stephen Powers
"Subway Art"-Martha Cooper, Henry Chalfant
"Freight Train Graffiti"- Roger Gastman, Darin Rowland, Ian Sattler
"Dondi White: Style Master General"- Andrew Witten, Dondi White, Michael White
"Spraycan Art"- Henry Chalfan, James Prigoff
Just to name a few... this is your homework assignment for the next year. Study hard, this will be on the final. forgive me if I forgot some.
Also if you haven't seen these I suggest watching them as well:
"Style Wars"
"Wild Style"
"Breakin' 1&2" (these are extra credit, they're just awesome)
P.S. if you listen carefully B+D, BD, MF, HV, and a couple others will teach you more than you'll ever learn on your own about this culture we all love.