Correction to: Evaluating the structural reform of outpatient psychotherapy in Germany (ES-RiP trial) - a qualitative study of provider perspectives - Poß-Doering, Regina; Hegelow, Martin; Borchers, Milena; Hartmann, Mechthild; Kruse, Johannes; Kampling, Hanna; Heuft, Gereon; Spitzer, Carsten; Wild, Beate; Szecsenyi, Joachim; Friederich, Hans-Christoph (BMC health services research, 2021)