| "The Meaning of Digital Technology", Widin, Hearing Instruments vol. 38, No. 11, Nov. 1987, pp. 28, 30, 32, 33 and 74. |
| Product Brochure for PHOX Programming Device of Micro-Technik GmbH. |
| Radio Shack Catalog #446 Copyright 1989 pp. 164-165. |
| Pluvinage and Benson, "New Dimensions in Diagnostics and Fitting", Hearing Instruments, Aug. 1988. |
| Widex Hearing Aid Company Inc., "Quattro", Apr. 1989. |
| Johnson, Pluvinage and Benson, "Digitally Programmable Full Dynamic Range Compression Technology "Oct. 1989. |
| Resound Incorporated, "The Resound Digital Hearing System" Aug. 1989. |
| Audio Engineering Society "Draft of AES Recommended Standard for Sound Reinforcement Systems Communications Interface". |