Вунтесмері, В., and М. Стоколос. “The Broadband Nonreciprocal Passive Devices of Very High Frequencies”. Visnyk NTUU KPI Seriia - Radiotekhnika Radioaparatobuduvannia, no. 37, May 2008, pp. 65-70, doi:10.20535/RADAP.2008.37.65-70.