1. Bending of a Circular Beam Resting on an Elastic Foundation," by Enrico Volterra;Journal of Applied Mechanics,1952
2. "Deflections of Circular Beams Resting on Elastic Foundations under Symmetric or Antisymmetric Loading " by Enrico Volterra. Proceedings Eighth International Cong. of Theoretical and Applied Mechanics Istanbul Turkey August 1952.
3. Deflections of Circular Beams Resting on Elastic Foundations Obtained by Methods of Harmonic Analysis," by Enrico Volterra;Journal of Applied Mechanics,1953
4. "Die Lehre von der Elastizitat und Festigkeit " by E. Winkler Prague Czechoslovakia 1867 p. 182.
5. "Die Berechnung des Eisenbahnoberbaues " by H. Zimmermann Berlin Germany 2d Ed. 1930.