order of 2 citations with same first author but in differents years

Hi, I have two citations with same first author and in two differents years. But in the final bibliography the order of the citation is not by year. For example : Citations: (Batchelor, 2007)blablabla(Batchelor, 2013) Bibliography: Batchelor, T. T., Gerstner, E. R., Emblem, K. E., Duda, D. G., Kalpathy-Cramer, J., Snuderl, M., … Jain, R. K. (2013). Improved tumor oxygenation and survival in glioblastoma patients who show increased blood perfusion after cediranib and chemoradiation. Proc Natl Acad Sci U S A, (7). Batchelor, T. T., Sorensen, A., & Tomaso, E. di. (2007). AZD2171, a pan-VEGF receptor tyrosine kinase inhibitor, normalizes tumor vasculature and alleviates edema in glioblastoma patients. Cancer Cell, 11(1), 83–95. I would that the 2007's citation be before the 2013's citation, how i can do that ? Thank you very much