Rosenkranz, M., O'Donnell, A., Verthein, U., Zurhold, H., Addison, M., Liebregts, N., Rowicka, M., Barták, M., Petruželka, B., Kaner, E.F., Martens, M.-S., "Understanding pathways to stimulant use: a mixed-methods examination of the individual, social and cultural factors shaping illicit stimulant use across Europe (ATTUNE): study protocol", BMJ open, 2025