Towards a theory of transformative social innovation: A relational framework and 12 propositions - Pel, Bonno; Haxeltine, Alex; Avelino, Flor; Dumitru, Adina; Kemp, René; Bauler, Tom; Kunze, Iris; Dorland, Jens; Wittmayer, Julia; Jørgensen, Michael Søgaard (Research Policy, 2020)