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:Primary antibodies were mouse anti-PLD1 antibody (Santa Cruz Biotechnology, Dallas, TX) diluted 1:100, or custom-made rabbit anti-ChKα antibody [24] diluted 1:250.
Category: