Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:All participants were randomised in the included trials, however, only four studies [32–35] specified the method used, one of which [33] described randomisation by sequential allocation according to age (and symptom duration) a method deemed inappropriate by van Tulder et al.
Category: