/**
* Get a title for the specified issn.
*
* @param issn the issn
* @return the title for the titleId or <code>null</code. if not found
*/
public TdbTitle getTdbTitleByIssn(String issn) {
if (issn != null) {
for (TdbPublisher publisher : tdbPublisherMap.values()) {
TdbTitle title = publisher.getTdbTitleByIssn(issn);
if (title != null) {
return title;
}
}
}
return null;
}
