1. Road Traffic Act Article 71 http://law.e-gov.go.jp/htmldata/S35/S35HO105.html
2. Tokyo Metropolitan Public Safety Commission Tokyo Metropolitan Public Safety Commission's Rule 9 1971
3. ITU-T P.1140 Speech communication requirements for emergency calls originating from vehicles https://www.itu.int/rec/T-REC-P.1140-201506-I/en
4. Soft constrained subband beamforming for hands-free speech enhancement;Grbic;Proc ICASSP 2002,,2002
5. Application of near-field optimum microphone arrays to hands-free mobile telephony;Ryan;IEEE Trans Vehicular Tech,2003