The semantic web - ISWC 2021 20th International Semantic Web Conference, ISWC 2021, virtual event, October 24-28, 2021 : proceedings - Hotho, Andreas 1973-; Blomqvist, Eva; Dietze, Stefan 1978-; Fokoue, Achille; Ding, Ying; Barnaghi, Payam; Haller, Armin; Dragoni, Mauro; Alani, Harith (Springer, 2021)