In order to avoid a list of references for this rather complicated topic, reference is made to an article by den Besten et al. (2003), where the primary references can be found.
Source: Besten et al. 2003: 276
Source: Besten et al. 2003: 273
Source: Besten et al. 2003: 274
Source: Besten et al. 2003: 275
Source: Besten et al. 2003: 274