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Multicolor interactive notepad
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Patent number 4,787,852
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Issue date Nov 29, 1988
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David W. Melnick
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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Programmed learning textbook
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Patent number 4,552,536
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Issue date Nov 12, 1985
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Andrew F. Kay
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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Invisible ink quiz game
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Patent number 4,514,177
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Issue date Apr 30, 1985
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Stry-Lenkoff Co.
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Leon G. Lenkoff
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3877155
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Patent number 3,877,155
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Issue date Apr 15, 1975
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G06 - COMPUTING CALCULATING COUNTING
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3823022
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Patent number 3,823,022
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Issue date Jul 9, 1974
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3789520
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Patent number 3,789,520
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Issue date Feb 5, 1974
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3617324
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Patent number 3,617,324
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Issue date Nov 2, 1971
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3516177
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Patent number 3,516,177
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Issue date Jun 23, 1970
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3511656
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Patent number 3,511,656
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Issue date May 12, 1970
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3499235
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Patent number 3,499,235
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3451143
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Patent number 3,451,143
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Issue date Jun 24, 1969
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3451779
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Patent number 3,451,779
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Issue date Jun 24, 1969
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3359656
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Patent number 3,359,656
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Issue date Dec 26, 1967
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3354558
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Patent number 3,354,558
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3327406
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Patent number 3,327,406
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3323231
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Patent number 3,323,231
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3302306
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Patent number 3,302,306
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3300879
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Patent number 3,300,879
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3281960
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3280483
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Patent number 3,280,483
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS
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3248808
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Patent number 3,248,808
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Issue date May 3, 1966
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G09 - EDUCATION CRYPTOGRAPHY DISPLAY ADVERTISING SEALS