Frangopoulos, Christos A.: 'Introduction' (Energy Engineering, 2017), 'Cogeneration: Technologies, Optimization and Implementation', Chap. 1, pp. 1-4, DOI: 10.1049/PBPO087E_ch1 IET Digital Library, https://digital-library.theiet.org/;jsessionid=1523pk3rfm7dj.x-iet-live-01content/books/10.1049/pbpo087e_ch1