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:The MIC of DPU compounds for wild-type M. tuberculosis H37Rv was determined essentially as described by measurement of AlamarBlue fluorescence (Ananthan et al., 2009; Maddry et al., 2009).
Category: