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 authors‚Äô approach to hepatic resection for CRLM has been described previously.(8,20,21) All operations included in this study were performed with therapeutic intent, where treatment of all disease while leaving behind an adequate liver remnant was believed to be technically feasible.
Category: