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:Further investigation on the chemical constituents of the extract resulted in the isolation of eight new chromones (1–8) and three new phenol derivatives (9–11) together with eight known compounds: sydowinin A (12) [4], pinselin (13) [5], sydowinin B (14) [5,6], aspergillusone B (15) [7], AGI-B4 (16) [8], diorcinol (17) [9], cordyol C (18) [10], and hydroxysydonic acid (19) [11] (Figure 1).
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