info on re-engineering

Help : We are looking for any product, book, course or any material in general to re-engineer ower application. It is an Informix-RDS' application and it has almost 600 source file. The application uses a database with almost 200 tables. We have no documentation at all of the software (if you don't consider the head of the older developers!) and a simple description of the meaning of the attributes of every single tables (but it is not frequently updated). As everybody can see, we are not in a very wonderful situation and so any kind of help is welcome. Many thanks in advance. P.S. Does anyone knows Internet sites where to find informations on reverse-engineering? Andrea Antonello Treviso - Italy