Books on Nudibranch ID

Hello! 

Looking for the best books on nudibranch identification, I'm interested  in any area but I dive off Maui, and any specific reccomendations for nudis found off the Hawaiian islands would be much appreciated! In or out of print is fine.

Tim 

https://blueplanetdc.com/shop/blue-planet-scuba/en/product/dive-gear/books/new-world-publications/reef-nudibranch-sea-slug-id-indo-pacific-10284

https://reefidbooks.com/ (every book on the Indo-Pacific)

this is the bible:

Nudibranch & Sea Slug Identification: Indo-Pacific, 2nd edition | Reef Environmental Education Foundation

Also available as e-book, it is now in second edition.  Also join the facebook ID groups, Nudibase is one of them and Nudibranch Central.

Hi! It's not a book however I've used this Sea Slugs of Hawaii site quite a bit.