1. Mugiono: Acustica 6 (1966) 185, Fig. 6. 2 Gösele, K.: Acustica 14 (1966) 320.
2. Kurtze, G., Tamm, K., Vogel, S.: Acustica 5 (1955) 226.
3. Vogel, S.: Acustica 6 (1956) 51, has made a special study of optimum configurations for such non-reflective terminations.
4. Exner, M. L., Bhme, W.: Aeuitioa 3 (1958) 105.
5. Oberst, H., Pischel, W.: DSIR-Berioht (Report) 1950.