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:While gene duplications in the MADS-box transcription factor family likely contributed to the earliest floral development regulatory networks [11,12,16-19], it is not clear whether these were single gene duplications or the product of polyploidization.
Category: