Hicks, Helen Segrave. The Recombination Rate Coefficient of Molecular Helium Ions in a Pulsed Afterglow at 1.86 Torr, dissertation, August 1972; (https://digital.library.unt.edu/ark:/67531/metadc164573/m1/1/: accessed September 22, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .