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:The histologic results are in conformity with those previously reported by several authors (Tansurat 1971; Viranuvatti and Stitnimankarn 1972; Bhamaraprarah et al. 1978; reviews in Schwartz 1980 and Flavell 1981; Riganti et al. 1989).
Category: