Rotational excitation and de-excitation of PN molecules by He atoms R. Toboła, J. Kłos, F. Lique, G. Chałasiński and M. H. Alexander A&A, 468 3 (2007) 1123-1127 Published online: 11 April 2007 DOI: 10.1051/0004-6361:20077339