“…We identify environmental innovations using appropriate indicators on patent data, according to their technological class, as in Marin and Lotti (). In Table , we report those patents with IPC (International Patent Classification) codes belonging to the groups selected by the OECD or the World Intellectual Property Organization (some case studies of the analysis patent activity in some technological domains [with application of specially selected IPC codes and classes] can be found in, for example, Streltsova, [biotechnology]; Rodriguez & Paredes, [hybrid vehicles industry]; Streletskiy, Zabavnikov, Aslanov, & Kotlov, [nanotechnology]; and Madvar et al, [petroleum industry]).…”