LEE, H. W., MOCEK, Tomáš, SHIN, H. J., LEE, D. G., HONG, K. H., NAM, C. H. Soft X-ray spectra of optical field ionized helium gas by a femtosecond Ti:Sapphire laser. In: CLEO / Pacific Rim`99. The Pacific Rim Conference in Optical-Field Ionized Plasma. Piscataway: IEEE, 1999, s. 932-933. ISBN 0-7803-5661-6.