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 most popular ESIPT probes are 3-hydroxychromones, which are largely used to investigate lipid membrane properties [14], as well as protein-membrane [15] and protein-nucleic acid [16, 17] interactions.
Category: