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:This situation is even more obvious if this prevalence is compared with that for age-matched populations, and it is in concert with the results of a casecontrol study that failed to establish a significant relationship between the occurrence of gallstones and GERD [29].
Category: