1. Sound radiation from a spherical vibrator;Hirayama;Nippon Electrical Communication Engineering,1937
2. Leitfaden zur Berechnung von Schallvorgängen
3. The directional properties of elliptical and spherical sound radiators;Karnovskiy;Journ. Techn. Phys. U.S.S.R.,1940
4. Caratteristiche di radiazione di una sfera rigida munita di calotta oscillante;Bordoni;Commentationes Pontificiae Academiae Scientiarum,1944