1. Norman DE. The invisible computer. John Wiley & Sons, New York, 1998
2. Matias E, MacKenzie IS, Buxton W. One-handed touchtyping on a QWERTY keyboard. Human-Computer Interaction 1996; 11: 1–27
3. Rosenberg R. Computing without mice and keyboards: text and graphic input devices for mobile computing. Doctoral dissertation, Department of Computer Science, University College, London, 1998
4. Goldstein M, Chincholle D. The Finger-Joint-Gesture wearable keypad. In: Brewster S, Dunlop M (eds) Second Workshop on Human-Computer Interaction with Mobile Devices. INTERACT'99, Edinburgh, Scotland, 31 August 1999; 9–18. Available at http://www.dcs.gla.ac.uk/mobile99/
5. MacKenzie IS, Zhang SX, Soukoreff RW. Text entry using soft keyboards. Behaviour & Information Technology 1999; 4: 235–244