1. QCD and Hadron Physics, Summary of the DNP Town Meeting held September 13–15, 2014 at Temple University in Philadelphia, PA, http://arxiv.org/ftp/arxiv/papers/1502/1502.05728.pdf .
2. G. Höhler, Pion-Nucleon Scattering, in Landoldt-Börnstein, Vol. I/9b2, edited by H. Schopper (Springer-Verlag, Berlin, 1983).
3. R.E. Cutkosky et al., Phys. Rev. D 20, 2804 (1979).
4. R.E. Cutkosky, C.P. Forsyth, R.E. Hendrick, R.L. Kelly, Phys. Rev. D 20, 2839 (1979).
5. Richard A. Arndt, John M. Ford, L. David Roper, Phys. Rev. D 32, 1085 (1985).