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 latter technique is also called mosaicplasty or the Osteochondral Autograft Transplant System (OATS), and it achieves a congruency of the articular surface in the loadbearing zone of the femoral condyle [1,2].
Category: