There are many XML books for you to choose from. However, only several of them are eligible for good quality. In my personal opinion, I enlist the following books for you to read:
1.XML Developer's Guide by Fabio Arciniegas
2.Step by Step XML by Michael Young
3.Applied XML Solutions by Benoit Marchal
4.Professional XML Databases by Kevin Williams
5.Inside XML by Steven Holzner
If you'd like to develop Oracle programs with XML, the "Professional Oracle 8i Application Programming with
Java, PL/SQL and XML by Michael Awai" would be a very nice option.
SEAN