Hänvisningar finns i följande patent|
| US7047681 | 30 jul 2003 | 23 maj 2006 | Rubbermaid Commercial Products LLC | Folding sign | | USD383080 | 26 okt 1995 | 2 sep 1997 | SEG Corporation | Caution signal | | USD401878 | 14 aug 1997 | 1 dec 1998 | Visual Technologies Incorporated | Flashing warning signal |
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