Number | Date | Country | Kind |
---|---|---|---|
82 04220 | Mar 1982 | FRX |
Number | Name | Date | Kind |
---|---|---|---|
3247491 | Du Vall | Apr 1966 | |
3601537 | Gueldenpfennig et al. | Jul 1968 | |
3961315 | Yokoyama et al. | Jun 1976 |
Number | Date | Country |
---|---|---|
021411 | Jan 1981 | EPX |
2261586 | Sep 1975 | FRX |
2069219 | Aug 1981 | GBX |
Entry |
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IBM Technical Disclosure Bulletin, vol. 23, No. 7A, Dec. 1980, J. Farran, "Detecting Marks Recorded as Extended One-Half Wavelengths", pp. 2974-2975. |