Godfraind, J.-M., Veraart, C., & Nicaise, M.-C. (1984). A Simple and Inexpensive Device for Applying a Calibration Pulse When Performing Intracellular-recording. Journal of Neuroscience Methods, 11(1), 61-63. https://doi.org/10.1016/0165-0270(84)90008-6 (Original work published 1984)