1. BlankenburgandTöpert IWTO Paris 18–20Jan 1978 Report No. 8.
2. deFries Dissertation TH Aachen1979.
3. deFries AltenhofenandZahn 6th Int. Wool Text. Res. Conf. (Pretoria 1980) V 529.
4. Ateya Diplomarbeit TH Aachen 1962 cf. Zahn Otten and Ateya Textil‐Rundschau 19 (1964)204.