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:6 See for example studies of Morocco by Haddad and Harrison (1993); Venezuela by Aitken and Harrison (1999); Bulgaria and Romania by Konings (2000); Russia by Yudaeva et al. (2003); the Czech Republic by Kosova (2004); and China by Abraham, Konings and Slootmaekers (2006). In the Chinese case, Abraham, Konings and Slootmaekers (2006) find positive horizontal spillovers for certain types of firms.
Category: