PhD Students' Mental Health and Well-Being: A Qualitative Study from Doctorates' Perspective from Five Spanish Universities - Amaya Ayala-Garcia; Marta Donat; Ariadna Cerdán-Torregrosa; Jose María Ramada; Guillermo García-González; Eva González-Menéndez; Elena Ronda-Pérez (International Journal of Educational Psychology, 2026)