Differential improvement in depressive symptoms for tDCS alone and combined with pharmacotherapy: An exploratory analysis from the Sertraline Vs. Electrical Current Therapy for Treating Depression Clinical Study - Brunoni, Andre Russowsky; Fraguas Junior, Renerio; Kemp, Andrew H.; Lotufo, Paulo A.; Benseñor, Isabela M.; Fregni, Felipe (International Journal of Neuropsychopharmacology, 2013)