I recommend this below book for learning flash technique :
"Mastering Canon EOS Flash Photography"
http://www.amazon.com/Mastering-Canon-EOS-Flash-Photography/dp/193395244X
I've found the one in Bukit Merah Public Library , it's new book and you can borrow it freely if you're member .
This book is quite new for release date and can be used for amateur , for the example they used 500D/T1i with 430EX II .
But for me the important part of this book was the description how to know the E-TTL works inside
.
Cheers .