Pintor L, Torres X, Navarro V, Matrai S, Gastó C. Is the type of remission after a major depressive episode an important risk factor to relapses in a 4-year follow up? J Affect Disord. 2004 Oct 15;82(2):291–6. doi: 10.1016/j.jad.2003.11.008. PMID: 15488260.