Non-Markovian entanglement dynamics of two spin-1/2 particles embedded in two separate spin star baths with tunable external magnetic fieldsX. Xiao, M. F. Fang, Y. L. Li, G. D. Kang and C. WuEur. Phys. J. D, 57 3 (2010) 447-453DOI: https://doi.org/10.1140/epjd/e2010-00065-0