1. J. P. Toennies, A. F. Vilesov, and K. B. Whaley, Phys. Today 54, 31 (2001).
2. E. Lugovoj, J. P. Toennies, S. Grebenev, et al., in Spectroscopy of Single Molecules and Clusters inside Super-fluid Helium Droplets, in Atomic and Molecular Beams, The State of the Art 2000, Ed. by R. Compargue (Springer, Berlin, 2000), p. 755.
3. S. Grebenev, M. Hartmann, A. Lindinger, et al., Physica B (Amsterdam) 280, 65 (2000).
4. S. Grebenev, B. G. Sartakov, J. P. Toennies, and A. F. Vilesov, Science 289, 1532 (2000).
5. C. Callegary, K. L. Lehmann, R. Schmied, and G. Scoles, J. Chem. Phys. 115, 10090 (2001).