Spin symmetry in Dirac negative-energy spectrum in density-dependent relativistic Hartree-Fock theoryHaozhao Liang, Wen Hui Long, Jie Meng and Nguyen Van GiaiEur. Phys. J. A, 44 1 (2010) 119-124DOI: https://doi.org/10.1140/epja/i2010-10938-6