Good horse sites?

So. In school I'm doing a position paper or whatever. So I chosesomething *you guessed it* about horses! I'm not gonna say what it is, but does anyone know and good websites that would give me good info on:

-growth of horses
-the basic anatomy
-and anything on when horses are done growing and maturing
-oh, and when they are ready to begin hard work

I know some of that is opinion, but and scientific sort of proof????

And...anything about Barbaro? Like info on the injury and what caused it??

Please websites only, not just telling me, because I have to make a bibliography.

THANKS!

-melanie

http://www.usatoday.com/sports/horse...ro-focus_x.htm

There is info at the bottom as well that explains why broken legs are so damaging to horses, etc.

http://www.angelfire.com/tx2/horseco...seanatomy.html

http://www.baileyshorsefeeds.co.uk/s...nitorchart.htm

Thanks!!! :]