Data Marketplaces with a Free Sampling Service. - Rafael Genés Durán; Oscar Esparza; Juan Hernández-Serrano; Fernando Román-García; Miquel Soriano; Achille Zappa; Martin Serrano; Susanne Stahnke; Birthe Böhm; Edgar Fries; Vasiliki Koniakou; Bruno Michel; et al. (SCC, 2022)