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 SR by Bhutta et al (13) was ruled out because it included studies up to 1999, and of the 3 remaining SRs, the 2 most recent were more comprehensive, and of both, the Cochrane
 JPGN Volume 60, Number 4, April 2015
 authorized reproduction of this article is prohibited.
 publication by Lazzerini and Ronfani (14) was chosen because it used GRADE methodology to evaluate the outcome of interest,
 cute diarrhea.
 www.jpgn.org
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 provided more information about the 6 pooled studies for this outcome, and provided as well a more exhaustive assessment of heterogeneity (which was not so high, I2 index 35
Category: