Wideband quality speech encoders with bit rates of 16-32 kbits/s. - P. J. Patrick; Costas S. Xydeas; Raymond Steele; Wai-kuen Cham (ICASSP, 1981)

Frequency compression of 7.6 kHz speed into 3.3 kHz bandwidth. - P. J. Patrick; Raymond Steele; Costas S. Xydeas (ICASSP, 1983)

Frequency Compression of 7.6 kHz Speech Into 3.3 kHz Bandwidth. - P. J. Patrick; Raymond Steele; Costas S. Xydeas (IEEE Trans. Commun., 1983)

Performance analysis of DPCM codecs operating on adaptively frequency mapped 7.6 khz speech. - Cumhur Cengiz Evci; P. J. Patrick (ICASSP, 1984)