Hi Hyuk.K, 

Books: I recommend 'New Insight into IELTS' (Cambridge), and 'focus on IELTS' New edition (Pearson Longman).

Websites: I suggest http://takeielts.britishcouncil.org/ , http://ielts-simon.com/ , and http://ieltsreader.webs.com/

Blake

Hello, Blake. Which book should I buy for IELTS?