Fokker, Adriaan D. 1934. “Brief [Letter] Prof. Dr. A.d. Fokker [Voorzitter Geluidstichting, Chair Sound Foundation] Aan [To] Prof. Dr. C. Zwikker [Secretaris Geluidstichting/Secretary Sound Foundation, 28.12.1934”. Brief [Letter] Prof. Dr. A.d. Fokker [Voorzitter Geluidstichting, Chair Sound Foundation] Aan [To] Prof. Dr. C. Zwikker [Secretaris Geluidstichting/Secretary Sound Foundation, 28.12.1934.
International Commission for Acoustics (ICA),, Felix Kolmer, Council of Federation of Acoustical Societies of Europe (FASE), Fritz Ingerslev, Internationale Vereinigung gegen den Lärm, Sound Foundation, and Dutch Society for Acoustics. n.d. “International Commission For Acoustics”.