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:‚Ä¶impact on overall energy cost. the Ec of the uphill sections we found can be compared with the results of other studies (table 2). the lowest Ec (tosi et al. 2009) was described for a short section lasting only 8 min while that of races lasting 1‚Äì2 h (Duc et al. 2011) up to 6 h 45 (this‚Ä¶
Category: