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\bibitem{Ryabchun_etal2007} Ryabchun, S., Tong, C. -yu E., Blundell, R., Kimberk, R., \& Gol{\textquoteright}tsman, G. (2007). Stabilisation of a terahertz hot-electron bolometer mixer with microwave feedback control. In \textit{Proc. 18$^{th}$ Int. Symp. Space Terahertz Technol.} (pp. 193--198).

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