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:Clinical reports of energetic stress in HCM hearts (14, 15) prompted us to measure mitochondrial respiration, mitochondrial copy number, ROS emission/scavenging, and calcium handling in these 2 HCM mouse models.
Category: