Pearman, C., Adams, C., Cox, S., Griffin, P., Smith, D., & Hughes, I. (2002). Polarization spectroscopy of a closed atomic transition: applications to laser frequency locking. Journal of Physics B: Atomic, Molecular and Optical Physics, 35(24), 5141-5151. https://doi.org/10.1088/0953-4075/35/24/315