Propagating waves in polar coronal holes as seen by SUMER & EIS D. Banerjee, L. Teriaca, G. R. Gupta, S. Imada, G. Stenborg and S. K. Solanki A&A, 499 3 (2009) L29-L32 Published online: 29 April 2009 DOI: 10.1051/0004-6361/200912059