Additional fields for each copy

I would use some bibliographical fields for each copy (for example publisher, date of publication...) I really don't know, if it's good idea to implement it this way, though. I think the way can be rework of library module, so each copy would correspond to node (so we coould use CCK) and will be automatically linked to other copies by means of nodereferenceThe the only task for library module would be to create node with circulation interface.