The Semantic Web - ISWC 2021 : 20th International Semantic Web Conference, ISWC 2021, Virtual Event, October 24-28, 2021, Proceedings - Hotho, Andreas; Alani, Harith; Barnaghi, Payam; Blomqvist, Eva; Dietze, Stefan; Ding, Ying; Dragoni, Mauro; Fokoue, Achille; Haller, Armin (Springer International Publishing, 2021)