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 data on avian influenza outbreaks in Vietnam from 2003 through to 2006 was provided by the Epidemiology Unit of the Department of Animal Health, Ministry of Agriculture and Rural Development of Vietnam; the characteristics of this dataset are explained elsewhere [6].
Category: