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:Such multi-way models have been applied to auto-fluorescence landscapes of food systems as well, like sugar (Bro 1999), meat (Moller and others 2003), fish oil (Pedersen and others 2002), milk (Boubellouta and Dufour 2008), yogurt (Christensen and others 2005), cheese (Christensen and others 2003), wines (AiradoRodriguez and others 2009), and edible oils (Guimet and others 2004; Sikorska and others 2004).
Category: