| Number | Name | Date | Kind |
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| 5870559 | Leshem et al. | Feb 1999 | |
| 5958008 | Progrebisky et al. | Sep 1999 | |
| 6003143 | Kim et al. | Dec 1999 | |
| 6012087 | Freivald et al. | Jan 2000 |
| Number | Date | Country |
|---|---|---|
| 05216827 | Aug 1993 | JPX |
| Entry |
|---|
| F. Douglis, T. Ball, Y. Chen, and E. Koutsofios, The AT&T Internet Difference Engine: Tracking and viewing changes on the web. Baltzer Science Publishers BV, 27-44 (1998). |
| F. van Harmelen and J. van der Meer, WebMaster: Knowledge-Based Verification of Web-Pages. 12.sup.th International Conference on Industrial and Engineering Applications of Artificial Intelligence and Expert Systems, IEA/AIE-99, Cairo, Egypt, 256-265 (1999). |