4Zipp P, Haider E, Halpern N, et al. Keyboard design through physiological strain measurements. Applied Ergonomics, 1983, 14(2) :117～122.
5Thompson D A, Thomas J, Cone J, et al. Analysis of the Tony variable geometry VDT keyboard. In: Proceedings of the Human Factors Society 54th Annual Meeting. Santa monica, CA: Human Factors and Ergonomics Society, 1990:565～569.
6Gilad I, Harel S. Muscular effort in four keyboard designs. Industrial Ergonomics,2000,26(1) : 1～7.
7Gopher D, Raij D. The chord keyboard Computer, 1984,11(1) :56～63.
8Gopher D, Raij D. Typing with a two-hand chord keyboard: Will the QWERTY become obsolete? IEEE transactions on systems, man, and cybernetics, 1988, 18(4):281～290.
9Life M A,Pheasant S T. An integrated approach to the study of posture in keyboard operation. Applied Ergonomics, 1984, 15(2):83～90
10Rose M J. Keyboard opening posture and actuation Force: implications for muscle over-use. Applied Ergonomics, 1991, 22(3) :198～203.
