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:To measure funding costs, we use the implicit interest rate on a bank’s interest-bearing liabilities, i.e., total interest expenses divided by interest-bearing liabilities (Demirgüç-Kunt and Huizinga, 2004).
Category: