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:All animal care and experimental procedures complied with the guidelines for the Care and Use of Laboratory Animals, formulated by the Ministry of Science and Technology of the People‚Äôs Republic of China and were approved by the Ethical Committee on Animal Experiments at Shanghai Jiao Tong University.
Category: