McKee, J. W., Lyne, A. G., Stappers, B. W., Bassa, C. G., & Jordan, C. A. (2018). Temporal variations in scattering and dispersion measure in the Crab Pulsar and their effect on timing precision. Monthly Notices of the Royal Astronomical Society, 479(3), 4216-4224. https://doi.org/10.1093/mnras/sty1727