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\bibitem{Okunev_etal1995} Okunev, 0., Dzardranov, A., Gol{\textquoteright}tsman, G., \& Gershenzon, E. (1995). Performances of hot{\textemdash}electron superconducting mixer for frequencies less than the gap energy: NbN mixer for 100 GHz operation. In \textit{Proc. 6$^{th}$ Int. Symp. Space Terahertz Technol.} (pp. 247--253).

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