Heavy quarkonium: progress, puzzles, and opportunities N. Brambilla, S. Eidelman, B.K. Heltsley, R. Vogt, G.T. Bodwin, E. Eichten, A.D. Frawley, A.B. Meyer, R.E. Mitchell, V. Papadimitriou et al. (57 more) Eur. Phys. J. C, 71 2 (2011) 1534 Published online: 08 February 2011 DOI: 10.1140/epjc/s10052-010-1534-9