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:For the historical data, intra-individual median LDL-C, HDL-C, TC, and HbA1c were used, and the CV of HbA1c (ratio of intrapersonal HbA1c standard deviation [SD]/mean HbA1c) was utilized as a measure of historical HbA1c variability (Waden et al., 2009).
Category: