The kinematics of the most oxygen-poor planetary nebula PN G 135.9+55.9 M. G. Richer, J. A. López, W. Steffen, G. H. Tovmassian, G. Stasińska and J. Echevarría A&A, 410 3 (2003) 911-916 Published online: 17 November 2003 DOI: 10.1051/0004-6361:20031267