Yagoubov, P., Kroug, M., Merkel, H., Kollberg, E., Hübers, H. - W., Schubert, J., et al. (1999). NbN hot electron bolometric mixers at frequencies between 0.7 and 3.1 THz. In _Proc. 10<sup>th</sup> Int. Symp. Space Terahertz Technol._ (pp. 238&ndash;246).