The physical and dynamical structure of Serpens - Two very different sub-(proto)clusters A. Duarte-Cabral, G. A. Fuller, N. Peretto, J. Hatchell, E. F. Ladd, J. Buckle, J. Richer and S. F. Graves A&A, 519 (2010) A27 Published online: 08 September 2010 DOI: 10.1051/0004-6361/200913919