Meson Mass Spectrum from Relativistic Equations in Configuration Space
  A method is described for solving relativistic quasi-potential equations in configuration space. The Blankenbecler-Sugar-Logunov-Tavkhelidze and an equal-time equation, both relativistic covariant two-body equations containing the full Dirac structure of positive and negative energy states, are studied in detail. These equations are solved for a system of two constituent quarks interacting through a potential consisting of a one-gluon exchange part with running coupling constant plus a linear confining potential which is mostly scalar and partly vector, and the spectrum of all light and heavy mesons is calculated. 
P.C. Tiemeijer and J.A. Tjon