Gell-Mann--Okubo Mass Formula for an SU(4) Meson Hexadecuplet
  Using a linear mass spectrum of an $SU(4)$ meson hexadecuplet, we derive the Gell-Mann--Okubo mass formula for the charmed mesons, in good agreement with experiment. Possible generalization of this method to a higher symmetry group is briefly discussed. 
L. Burakovsky and L.P. Horwitz