Beyond perception. Do pre-service geography teachers understand education for sustainable development? - Nguyen, Thao Phuong; Hoang, Tuan Thai; Trinh, Thach Quang; Muñiz Solari, Osvaldo; Nguyen, Anh Ngoc; Schrüfer, Gabriele; Xuan Do, May Thi; Nguyen, Thang Huu; Ni Nguyen, Thi Ha (International Research in Geographical & Environmental Education, 2026)