Besides the fine standard documents and the many hypertexts on the World-Wide Web that I linked or that can be found via web search, there are quite a few good books and articles about Unicode and the related subjects of writing systems, multilingual text processing, internationalization and localization, character encoding, typesetting and font handling (but no third-party books with Unicode in the title yet).
I suggest you take a look at the Unicode bibliography (BibTeX source unicode.bib) maintained by Nelson Beebe <email@example.com> into which I have added a few entries so that it accurately displays my literature list. If I ever find the time to write a commented bibliography, I will place it here. I found a lot of good reading material for my thesis in the well-organized Dutch libraries.
Further questions can be posted to the Usenet newsgroup comp.std.internat or the mailing list firstname.lastname@example.org which started as email@example.com and is archived in ftp://ftp.unicode.org/Public/MailArchive/ and to which you can subscribe with:
echo subscribe firstname.lastname@example.org unicode | Mail -s subscribe email@example.com
November 27, 1998