| Number | Date | Country | Kind |
|---|---|---|---|
| 3-85230 | Apr 1991 | JPX | |
| 3-59803 | Jul 1991 | JPX | |
| 3-190088 | Jul 1991 | JPX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 775716 | Williams | Nov 1904 | |
| 806920 | Rossi | Dec 1905 | |
| 970398 | Sapp | Sep 1910 | |
| 1003540 | Sterrett | Sep 1911 | |
| 3961655 | Nattrass et al. | Jun 1976 | |
| 4203479 | Mathews | May 1980 | |
| 4817824 | La Fleur et al. | Apr 1989 | |
| 4946478 | Davis et al. | Aug 1990 |
| Number | Date | Country |
|---|---|---|
| 0338181 | Oct 1989 | EPX |
| Entry |
|---|
| "Powder Handling and Processing", International Journal of Storing, Handling and Processing, pp. 259-261, Sep. 1990. |