Two-step verification as a safety measure for learners and teachers: an attempt to implement it in a real environment

1. Arrieta, A.G.
2. Sánchez, D.L.
3. Lázaro, Á.L.S.
4. Lancho, M.B.P.
5. García-Bermejo-Giner, J.R.
6. Simón, J.A.H.
7. Cruz, P.I.V.