Hu, M., Wei, F., Peng, Y., Huang, Z., Yang, N. and Li, D. (2019) “Read + Verify: Machine Reading Comprehension with Unanswerable Questions”, Proceedings of the AAAI Conference on Artificial Intelligence, 33(01), pp. 6529-6537. doi: 10.1609/aaai.v33i01.33016529.