| Number | Name | Date | Kind |
|---|---|---|---|
| 3726952 | Boden et al. | Apr 1973 | |
| 4065410 | Schafer et al. | Dec 1977 | |
| 4218543 | Weber et al. | Aug 1980 | |
| 4269945 | Vanderhider et al. | May 1981 | |
| 4341875 | Visger et al. | Jul 1982 | |
| 4435349 | Dominquez et al. | Mar 1984 | |
| 4442235 | Taylor et al. | Apr 1984 |
| Entry |
|---|
| Journal of Cellular Plastics, Sep./Oct., 1981, pp. 268-273. |