Claeys, W., Cornet, A., Lorent, V., & Fussen, D. (1985). H(3s) Beam Production By Laser Excitation of Metastable Hydrogen-atoms in An Electric-field .1. Experiment. Journal of Physics B: Atomic, Molecular and Optical Physics, 18(18), 3667-3672. https://doi.org/10.1088/0022-3700/18/18/007 (Original work published 1985)