Accurate comparison of Hel, NeI photoionization and He(23, 1 S), Ne(3s 3 P s,3 P 0) penning ionization of argon atoms and dimers - Kraft, T.; Bregel, T.; Ganz, J.; Harth, K.; Ruf, M. -W.; Hotop, H. (Springer, 1988)
http://dx.doi.org/10.1007/BF01425766
Keywords: U