Important Books
1) Menezes
2) Hankerson, Vanstone, Menezes
3) Koblitz (2 books)
3) Blake, Seroussi, Smart
4) Washington
5) Cohen, Frey, Avanzi
6) Tilborg

See Google Books:
http://books.google.com/books?q=elliptic+curve+cryptography&btnG=Search+Books