Detecting the Presence of Speech Using ADPCM Coding. - Ronald W. Schafer; K. Jackson; John J. Dubnowski; Lawrence R. Rabiner (IEEE Trans. Commun., 1976)

A Microprocessor Log PCM/ADPCM Code Converter. - John J. Dubnowski (IEEE Trans. Commun., 1978)

Variable rate coding. - John J. Dubnowski; Ronald E. Crochiere (ICASSP, 1979)