Doppler-free resonance ionization spectroscopy of the He 1s(2) S-1-1s2s S-1 transition at 120.3 nm - Bergeson,SD; Balakrishnan,A; Baldwin,KGH; Lucatorto,TB; Marangos,JP; McIlrath,TJ; OBrian,TR; Rolston,SL; Vansteenkiste,N (AIP PRESS, 1997)