How to cite a reference of a study that appears in a review paper [duplicate]

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• Getting secondary citations right 1 answer

I am actually writing a review paper and I am getting a little confused with how to cite some studies. The main problem is when I find a review paper (eg: Smith et al., 2011) that cites a study (eg: Alvira et al., 2000). What should I cite in my review paper, the review paper Smith et al., 2011 or the original study Alvira et al., 2000??.

Thanks.