Vector quantization of speech waveforms. - Hüseyin Abut; Robert M. Gray; Guillermo Rebolledo (ICASSP, 1981)

Rate-distortion speech coding with a minimum discrimination information distortion measure. - Robert M. Gray; Augustine H. Gray Jr.; Guillermo Rebolledo; John E. Shore (IEEE Trans. Inf. Theory, 1981)

A Multirate Voice Digitizer Based Upon Vector Quantization. - Guillermo Rebolledo; Robert M. Gray; John P. Burg (IEEE Trans. Commun., 1982)