1. (a) (1937) Verfahren zur Herstellung von Polyurethanes bzw. Polyharnstoffen. DE Patent 728,981 13 Nov 1937; (b) Bayer O (1947) Das Di-Isocyanat-Polyadditionsverfahren (Polyurethane). Angew Chem 59:257–272
2. Thomson T (2004) Polyurethanes as specialty chemicals: principles and applications. CRC Press, Boca Raton
3. Woods G (1990) The ICI polyurethanes book, 2nd edn. Wiley, New-York
4. Plastics – the Facts (2012) Plastics Europe, http://www.plasticseurope.org/Document/plastics-the-facts-2012.aspx . Accessed on 25 Nov 2012
5. Ulrich H (2001) The chemistry of isocyanates. Wiley, Chichester