[1] David E. Root, Jan Verspecht, David Sharrit, John Wood, and Alex Cognata, “Broad-Band Poly-Harmonic Distortion (PHD) Behavioral Models From Fast Automated Simulations and Large-Signal Vectorial Network Measurements”, IEEE Transactions on Microwave Theory and Techniques, Vol 53, No. 11, November 2005, pp. 3656-3664.
[2] Jan Verspecht and David E. Root, “Polyharmonic Distortion Modeling”, IEEE Microwave Magazine, Vol. 7, Issue 3, June 2006, pp. 44-57.