The masses of the mesons and baryons. Part I. The Integer Multiple Rule
  From the well-known decays of the particles follows that the mesons and baryons consist of a $\gamma$-branch and a neutrino branch. From the well-known masses of the particles follows that the masses of the $\gamma$-branch particles are integer multiples of the mass of the $\pi^0$ meson, within 3%, in spite of differences in spin, isospin, strangeness and charm. The average factor in front of the integer multiples of $m(\pi^0)$ of the $\gamma$-branch particles is $1.0073 \pm 0.0184$. The masses of the $\nu$-branch particles are integer multiples of the mass of the $\pi^\pm$ mesons, times a factor $0.86 \pm 0.02$. The existence of the integer multiple rule can be verified from the Particle Physics Summary using a calculator. 
E. L. Koschmieder