Yeap, K. H., S. S. Ong, H. Nisar, K. C. Lai, and C. A. Ng. “Attenuation in Superconducting Circular Waveguides”. Advanced Electromagnetics, vol. 5, no. 2, Sept. 2016, pp. 34-38, doi:10.7716/aem.v5i2.388.