Variable bit rate ADPCM via arithmetic coding. - Craig R. Watkins; Sam Crisafulli; Robert R. Bitmead; Robert Orsi (ICASSP (1), 1994)

Improving 16 kb/s G.728 LD-CELP speech coder for frame erasure channels. - Craig R. Watkins; Juin-Hwey Chen (ICASSP, 1995)

Destabilization effects of adaptive quantization in ADPCM. - Craig R. Watkins; Robert R. Bitmead; Sam Crisafulli (IEEE Trans. Speech Audio Process., 1995)