The following is a paper by H. Aspden published in Hadronic Journal, v. 9, pp. 137-140 (1986).
Abstract: Attention is drawn to a remarkable energy correlation which uniquely determines the rest-mass energies of all the intermediate particles in the electron-proton energy spectrum. The correlation formula uses a classical expression formulated by J. J. Thomson, which represents the charge of a particle as confined within a sphere of radius 2e2/3mc2.
The full text of this paper may also be seen in PDF format as Paper No. 2 in the author's 1996 book Aether Science Papers which is of record in the author's website www.aspden.org.