Psilocybin with psychological support for treatment-resistant depression: an open-label feasibility study. - Carhart-Harris RL; Bolstridge M; Rucker J; Day CM; Erritzoe D; Kaelen M; Bloomfield M; Rickard JA; Forbes B; Feilding A; Taylor D; Pilling S; et al. (The lancet. Psychiatry, 2016)