I am thrilled to hear that others are bringing books for the library. I am returning to SP in September and will have an entire duffle bag filled with books, arts/craft supplies, pens/pencils/erasers, etc. for the library.
The library's website //ambergriscaye.com/library suggests that you contact their senior librarian, Iracela Acosta to assist with a letter for customs purposes. That is what I have done. Her e-mail is firstname.lastname@example.org. Very nice lady. I have been e-mailing her back and forth since December & I am very much looking forward to meeting her.