Multiple attempts can be made to match received information associated with a work and one of multiple identifiers stored in a database. Each of the identifiers in the database is uniquely associated with one of a plurality of specific works. A first search can be made to determine if an identifier in the received information includes an identifier that matches one of identifiers stored in the database. If the identifier in the received information does not match any of the identifiers in the database, a second matching attempt can be made to determine if the received attributes match attributes of a work associated with one of the identifiers in the database. Based on the results of the matching, various actions can be taken to associate or assign one of the unique identifiers with the work related to the received information.