php and XML BibTeX

Hi - Currently on my web site, book and article references are just stored in the database. While it works, I actually would like to move that out of the database and to an XML file, the reason being is that if/when I need to add fields etc. to the referenced sources, it's a lot easier to just edit a text file than modify database and recode my form interface for modifying the database. Also, there's an existing XML format for bibTeX and there already are tools to go from that to "real" bibTex, which I may need to do at some point. What I'm hoping is that already exists some php classes / functions for dealing with the XML bibTeX but I haven't found them. Anyone know of any?