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\bibitem{Karpov_etal1999} Karpov, A., Blondel, J., Voss, M., \& Gundlach, K. H. (1999). A three photon noise SIS heterodyne receiver at submillimeter wavelength. \textit{IEEE Trans. Appl. Supercond.}, \textit{9}(2), 4456--4459.

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