1. Schade, F., Dissertation (Aachen 1962).
2. Schade, F. undH. Zahn, Angew. Chem.74, 904 (1962).
3. Zahn, H., F. Schade undE. Siepmann, Leder14, 299 (1963).
4. Gustavson, K. H., The Chemistry and Reactivity of Collagen (London 1956).
5. Lennox, F. G. undH. M. Forss, J. Soc. Leather Trades' Chemists36, 322 (1952).