The enactment of socio-technical transition pathways: A reformulated typology and a comparative multi-level analysis of the German and UK low-carbon electricity transitions (1990–2014) Frank W. Geels; Florian Kern; Gerhard Fuchs; Nele Hinderer; Gregor Kungl; Josephine Mylan; Mario Neukirch; Sandra Wassermann Research Policy 2016 45(4), 896-913