Environmental education for youth and adults: a bibliometric analysis of research Kateryna Onopriienko, Volodymyr Onopriienko, Yurii Petrushenko and Iryna Onopriienko E3S Web Conf., 234 (2021) 00002 Published online: 02 February 2021 DOI: 10.1051/e3sconf/202123400002