sentence: 미들턴, 리차드 (1990) "Studying Popular Music". Open University Press.
subject_entity: {'word': '1990', 'start_idx': 10, 'end_idx': 13, 'type': 'DAT'}
object_entity: {'word': 'Studying Popular Music', 'start_idx': 17, 'end_idx': 38, 'type': 'POH'}