Number | Name | Date | Kind |
---|---|---|---|
1106150 | Martin | Aug 1914 | |
1888039 | Huff | Nov 1932 | |
2331140 | Schmidt | Oct 1943 | |
2816323 | Munger | Dec 1957 | |
3562056 | Olson | Feb 1971 | |
3848034 | Schaefer | Nov 1974 | |
4112979 | Widdicombe | Sep 1978 | |
4578235 | Schmidgall et al. | Mar 1986 | |
4670315 | Hillemeier et al. | Feb 1987 | |
4751799 | Ditcher et al. | Jun 1988 | |
4834428 | Pritchatt | May 1989 |
Number | Date | Country |
---|---|---|
2918275 | Jul 1979 | DEX |
Entry |
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Product catalog of Friedrichsfeld GmbH Technical Plastics Division, "Corrosion protection for concrete and reinforced concrete pipes, special profiles, bowls and manholes with the BKU-system". |
Southwest Concrete Products brochure entitled "Precast Concrete Manholes". |