1. www.esa.int/SPECIALS/Herschel/ ; www.sron.nl/ ; www.sofia.usra.edu/
2. H.-W. Hubers, IEEE J. Sel. Top. Quant. Electron. 14, 378 (2008).
3. Mark Lee, L. N. Pfeiffer, K. W. West, and K. W. Baldwin, Appl. Phys. Lett. 78, 2888 (2001).
4. D. V. Morozov, K. V. Smirnov, A. V. Smirnov, V. A. Lyakhov, and G. N. Gol’tsman, Fiz. Tekh. Poluprovodn. 39, 1117 (2005) [Semiconductors 39, 1082 (2005)].
5. E. L. Shangina, K. V. Smirnov, D. V. Morozov, V. V. Kovalyuk, G. N. Gol’tsman, A. A. Verevkin, and A. I. Toropov, Izv. RAN, Ser. Fiz. 74, 110 (2010).