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\bibitem{Loudkov_etal2005} Loudkov, D., Tong, C. - Y. E., Blundell, R., Kaurova, N., Grishina, E., Voronov, B., et al. (2005). An investigation of the performance of the waveguide superconducting HEB mixer at different RF embedding impedances. In \textit{Proc. 16$^{th}$ Int. Symp. Space Terahertz Technol.} (pp. 226--229).

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