Oracle provides extensive documentation for the 10g Release 2 (10.2) family. For a "deep" technical dive, you should refer to these specific guides: Database Concepts

The 10.2.0.4 patch set (Patch 6810189) is officially hosted on My Oracle Support. Access requires a paid support contract.

Oracle 10g Release 2 (10.2.0.4) is a "vintage" software version by modern standards: Premier Support for 10gR2 10.2.0.4 Database ends July 2010