Pinceaux, J.-P.; Maury, J.-P.; Besson, J.-M. (1979). "Solidification of helium, at room temperature under high pressure" (PDF). Journal de Physique Lettres. 40 (13): 307–308. doi:10.1051/jphyslet:019790040013030700. S2CID 40164915. Wheeler, John C. (1997). "Electron Affinities ...