private String createSourceBookKey(final IExaltedSourceBook source) {
   return "ExaltedSourceBook." + source.getId(); // $NON-NLS-1$
 }
 private String createPageKey(String id, IExaltedSourceBook source) {
   return source.getId() + "." + id + ".Page"; // $NON-NLS-1$ //$NON-NLS-2$
 }