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\bibitem{Smirnov_etal2008} Smirnov AV, Larionov PA, Finkel MI, Maslennikov SN, Voronov BM, Gol{\textquoteright}tsman GN. NbZr films for THz phonon-cooled HEB mixers. In: Proc. 19$^{th}$ Int. Symp. Space Terahertz Technol. Groningen, Netherlands; 2008. p. 44--7.

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