The masses of the mesons and baryons. Part III. The size of the   particles
  The size of the stable elementary particles is investigated with the standing wave model. The particle size follows from the magnitude of the radiation pressure. It is shown that the outward directed radiation pressure is balanced by the inward directed elastic force per unit area in the cubic nuclear lattice, provided that the sidelength of the lattice is 10^(-13) cm, which agrees with the measured radius of the proton r = 0.8 \times 10^(-13) cm, within the uncertainty of the parameters. 
E. L. Koschmieder