Leo, P., Whittingham, I.B., Venturi, V., and Babb, J.F. (2001) Ultracold collisions of metastable helium atoms. Physical Review A (Atomic, Molecular and Optical Physics), 64 (4). 042710. pp. 1-8.

Leo, P.J., Peach, G., and Whittingham, I.B. (2000) Investigation of sodium-helium interaction potentials. Journal of Physics B: Atomic, Molecular and Optical Physics, 33 (21). pp. 4779-4797.