Tur, G. and Marin, V.I. and Havemann, Leo and Keefer, J. and Marsh, J.D. and Nascimbeni, F. and Crump, H. and Baker, N. and Garcia Vallejo, M.C. (2018) Open Education as a threshold concept in Teacher Education: a theoretical framework for further research. In: OER18: Open to All, 18-19 Apr 2018, Bristol, UK. (Unpublished)