Conditions and instability in f(R) gravity with non-minimal coupling between matter and geometryJun Wang, Ya-Bo Wu, Yong-Xin Guo, Fang Qi, Yue-Yue Zhao and Xiao-Yu SunEur. Phys. J. C, 69 3-4 (2010) 541-546DOI: https://doi.org/10.1140/epjc/s10052-010-1419-y