gets the value of the isbn property . concode_field_sep List<String> publicationPlace concode_elem_sep List<ResponsibleParty> performer concode_elem_sep String isbn concode_elem_sep ResponsibleParty publisher concode_field_sep List<String> getPublicationPlace concode_elem_sep List<ResponsibleParty> getPerformer concode_elem_sep void setISBN concode_elem_sep AudioVisual withPerformer concode_elem_sep AudioVisual withPerformer concode_elem_sep AudioVisual withISBN concode_elem_sep ResponsibleParty getPublisher concode_elem_sep AudioVisual withPublisher concode_elem_sep AudioVisual withPublicationPlace concode_elem_sep AudioVisual withPublicationPlace concode_elem_sep void setPublisher
String function ( ) { return isbn ; }