Koçak Tümer, N. B. “Analysis of Postgraduate Theses Prepared for the Preschool Period on ‘Environmental Education’ Conducted Between 2011 and 2020 in Turkey: A Content Analysis”. Psycho-Educational Research Reviews, vol. 10, no. 3, Dec. 2021, pp. 30-43, doi:10.52963/PERR_Biruni_V10.N3.03.