Heavy-Quark QCD Exotica
  This review presents an overview of the remarkable progress in the field of heavy-quark exotic hadrons over the past 15 years. It seeks to be pedagogical rather than exhaustive, summarizing both the progress and specific results of experimental discoveries, and the variety of theoretical approaches designed to explain these new states. 
Richard F. Lebed, Ryan E. Mitchell, Eric S. Swanson
hep-ph hep-ex nucl-ex nucl-th