Ab initio calculations of energy transfer and non-additivity in the He-Ne laser system A. S. Shalabi, M. M. Assem, S. Abd El-Aal, M. A. Kamel and M. M. Abd El-Rahman Eur. Phys. J. D, 7 2 (1999) 181-189 Published online: 15 September 1999 DOI: 10.1007/s100530050364