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 application of PBM for the management of postmastectomy lymphedema is corroborated by solid data [15, 16] and clinical findings now suggest a beneficial impact on the prevention of radiationinduced oral mucositis [17–20].
Category: