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:…studies, comprising the possibility of high throughput with phenotypic characterization upon drug stimuli and may be coupled with high content screening platforms for identification of toxic compounds, as previously described for other 3D systems (Celli et al. 2014; Wenzel et al. 2014).
Category: