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\bibitem{Ryabchun_etal2009} Ryabchun SA, Tretyakov IV, Finkel MI, Maslennikov SN, Kaurova NS, Seleznev VA, et al. NbN phonon-cooled hot-electron bolometer mixer with additional diffusion cooling. In: Proc. 20$^{th}$ Int. Symp. Space Terahertz Technol. Charlottesville, USA; 2009. p. 151--4.

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