1. Syskevasia—Manual on Packaging Materials and Methods, 2nd edn. 10P, Athens (1991).
2. US Patents 5,054,632, 4,877,141, 4,863,046, 4,805,788, 4,946,053, 4,381,061;
3. French Patent 90 987;
4. Japanese Patents 7,126,310 and 606,383;
5. UK Patent 2,218,395.