Song, K., B. Wang, Z. Feng, R. Liu, and F. Liu. “Controlling the Amount of Verbatim Copying in Abstractive Summarization”. Proceedings of the AAAI Conference on Artificial Intelligence, vol. 34, no. 05, Apr. 2020, pp. 8902-9, doi:10.1609/aaai.v34i05.6420.