1. Electron Hole Droplets in Semiconductors, Ed. by C. D. Jeffries and L. V. Keldysh (North-Holland, Amsterdam, 1983).
2. S. Schmitt-Rink, D. S. Chemla, and D. A. B. Miller, Adv. Phys. 38, 89 (1989).
3. P. Vashishta and R. K. Kalia, Phys. Rev. B 25, 6492 (1982).
4. V. D. Kulakovskii, E. Lach, A. Forchel, and D. Grützmacher, Phys. Rev. B 40, 8087 (1989).
5. T. M. Burbaev, E. A. Bobrik, V. A. Kurbatov, M. M. Rzaev, N. N. Sibel’din, V. A. Tsvetkov, and F. Shéffler, Pis’ma Zh. Éksp. Teor. Fiz. 85, 410 (2007) [JETP Lett. 85, 331 (2007)].