Method: W.H. Freeman: “Helplessness: On Depression, Development, and Death" ISBN 0-7167-0752-7. (Paperback reprint edition, W.H. Freeman, 1992, ISBN 0-7167-2328-X)
K. Szklarczyk et alia: “Opioid-Dependent Regulation of High and Low Fear Responses in two Inbred Mouse Strains" Behav. Brain Res 292: 95-101, 2015
Guilherme dos Santos et alia: “Antidepressive-like effects of electroacupuncture in rats" Physiology & Behavior 93: 155-159, 2008
Kademian et alia: “Biphasic effects of adrenal steroid on learned helplessness behavior by inescapable shock" Neuropsychopharmacology 30: 58-66, 2005
Borsini & Cesana: “Mechanisms of action of flibanserin in the learned helplessness in rats." European Journal of Pharmacology 433: 81-89, 2001
Grau et alia: “Long-term analgesia and activation of the opiate system" Science 213:1409-1411, 1981