This book only scratches the surface of each of the areas it covers. Appendix B lists some resources where you can pursue any of the areas brought up here in much more depth. I've organized the resources by topic, because there are certain to be some areas you're more interested in than others, and I've annotated the references so you can direct your search more effectively.
Some areas of semantics are changing rapidly. (What we think the ancient Greeks thought about semantics isn't changing very fast, but standards in the upper level of the Semantic Web stack are turning over on a quarterly basis.) As such I will attempt to keep this information current and provide live links at http://www.semanticsinbusiness.com. The reference material includes books, conferences, discussion groups, and Web sites that will help you take these concepts further.