Leal-Sevillano, C. A., J. A. Ruiz-Cruz, J. R. Montejo-Garai, and J. M. Rebollar,  "Waveguide Devices with Integrated Polarization Twist for Broadband Applications",  Proc. 2011 USNC/URSI National Radio Science Meeting, pp. 1, July, 2011.

Ruiz-Cruz, J. A., J. R. Montejo-Garai, J. M. Rebollar, and K. A. Zaki,  "Waveguide filters with elliptical function response: Overview and results of different implementations",  International Journal of RF and Microwave Computer-Aided Engineering, vol. 17, no. 1, pp. 63-69, Jan., 2007.