The semantic web 16th international conference, ESWC 2019, Portorož, Slovenia, June 2-6, 2019 : proceedings - Hitzler, Pascal; Fernández, Miriam; Janowicz, Krzysztof 1979-; Zaveri, Amrapali 1984-; Gray, Alasdair J.G; Lopez, Vanessa; Haller, Armin; Hammar, Karl (Springer, 2019)