Question: who sang blue moon in the 1950's
[{'answer': 'Elvis Presley', 'provenance': [{'wikipedia_id': '1826002', 'title': 'Blue Moon (1934 song)', 'start_paragraph_id': 1, 'start_character': 581, 'end_paragraph_id': 1, 'end_character': 594, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]