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:Additionally, the only known locality of H. axyridis in western China is in Xinjiang, very close to the China-Kazakhstan border
and relatively close to the railway, which crosses the
Turkestan-Siberian Railway (Poutsma et al. 2008).
Category: