1. Laengle J., Ger. Offen. DE 3,221,463 (Cl. CO4 B 15/02), 20 Jan 1983, Appl. 81/2, 577, 10 Jun (1981) 10.
2. Quante H., Ger. Offen. DE 3,101, 336 (C1.B28C 5/00), 26 Aug 1982, Appl. 17 Jan (1981) 12.
3. Buecking G., Seeger G., Schawarz H.G., Ger. Offen. DE 3,247,009 (Cl. B28B 15 /00), 20 Jun 1984, Appl. 18 Dec. (1982) 13.
4. Yoshida S., Kulmagai H., Jpn. Kokai Tokkyo Koho JP 61, 177, 176 [86 117, 176] (Cl. C4B 38/08), 04 Jun 1986, Appl. 84 /239, 942, 14 Nov (1984) 2.