1. For additional overviews see e.g. Hauschildt (2004), pp. 3 ff., Macharzina (2003), pp. 666 ff., Brockhoff (1999a), pp. 35 ff. and Gerpott (1999), pp. 39 ff.
2. See Barnett (1953), p. 7
3. See Burgelman et. al. (2004), p. 246
4. See Vahs/ Burmester (2005), p. 44 and Gerpott (1999), p. 49
5. See Gerpott (1999), p. 39