Li, S., X. Li, L. Shang, X. Jiang, Q. Liu, C. Sun, Z. Ji, and B. Liu. “HopRetriever: Retrieve Hops over Wikipedia to Answer Complex Questions”. Proceedings of the AAAI Conference on Artificial Intelligence, vol. 35, no. 15, May 2021, pp. 13279-87, doi:10.1609/aaai.v35i15.17568.