“Cognitive effects of anodal transcranial direct current stimulation and high-dose cocoa flavonoids on an acutely sleep-deprived, highly educated population: a proposed single-center, phase II, randomized, placebo-controlled, double-blind, factorial study”, PPCR, vol. 4, no. 1, pp. 27–35, Jul. 2018, Accessed: May 05, 2024. [Online]. Available: https://journal.ppcr.org/index.php/ppcrjournal/article/view/63