 
                 Patent Grant
 Patent Grant
                     4075465
 4075465
                    | Entry | 
|---|
| "Plastic Keyboard Translator" by C. C. Kling, IBM Tech. Disc. Bulletin, vol. 4, No. 12, May 1962. | 
| "Changeable Array Keyboard" by Cooper and Harrison, IBM Tech. Dicl. Bull., vol. 11, No. 5, Oct. 1968. | 
| "Keybaord Overlay" by R. G. Cross, IBM Tech. Discl. Bull., vol. 15, No. 1, June 1972. |