[1] Speech Recognition Grammar Specification Version 1.0 ( 版) http://www.w3.org/TR/speech-grammar/
[2] Speech Recognition Grammar Specification Version 1.0 () https://www.w3.org/TR/2004/REC-speech-grammar-20040316/
[7] 関連: ABNF, documentation comment
[4] SRGS Grammar XML Reference () https://msdn.microsoft.com/ja-jp/library/hh361653
[5] 音声認識文法の作成方法 — OpenHRI Manual () http://openhri.readthedocs.io/en/latest/workingwithgrammar-ja.html
[6] Semantic Interpretation for Speech Recognition (SISR) Version 1.0 () https://www.w3.org/TR/semantic-interpretation/