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2. P. Blanco (Proc. Conf. Heliotechn. Develop. Dhahran 2 [1976] 415/423) 3. U. Heidtmann (German Solar Forum, Hamburg, [1977] 349/362)
3. U. Heildtmann (German Solar Forum, Hamburg, [1976] 415/423
4. Bechtel Corp. (NTIS Rept. SAND-77–8176 [1977])
5. L. E. Rybakova, M. Mamedov (Geliotekhnika 13, No 3 [1977] 45/48.- Appl. Solar En. 13, No 3 [1977] 34/36)