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 commercial vaccines, Gavac and TickGARD, contained the recombinant R. microplus Bm86 gut antigen (Willadsen et al. 1989; Rand et al. 1989; Rodríguez et al. 1994; de la Fuente and Kocan 2003; de la Fuente et al. 2007a).
Category: