Duysens, J., & Gybels, J. (1988). The Automated Measurement of Hindlimb Flexor Reflex of the Rat As a Substitute for the Tail-flick Assay. Journal of Neuroscience Methods, 24(1), 73-79. https://doi.org/10.1016/0165-0270(88)90035-0 (Original work published 1988)