Question: when was harry potter and the philosopher's stone book published
[{'answer': '1997', 'provenance': [{'wikipedia_id': '48648', 'title': "Harry Potter and the Philosopher's Stone", 'start_paragraph_id': 2, 'start_character': 62, 'end_paragraph_id': 2, 'end_character': 66, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '48648', 'title': "Harry Potter and the Philosopher's Stone", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 628, 'bleu_score': 0.641890959261602, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3903152813768255197}, 'section': 'Section::::Abstract.'}]}]