Tan, X. -M., Kuang, X. -Y., Zhou, K. -W., Lu, C., & Zhu, Q. -S. (2006). Spin-singlet contributions to zero-field splitting of a 3d4 ion at a distorted octahedral site and applications to Cr2+ ions in Rb2CrCl4 and CrF2. Journal of Physics Condensed Matter, 18(5), 1705. doi:10.1088/0953-8984/18/5/023
Tan, X. -M., Kuang, X. -Y., Zhou, K. -W., Lu, C., & Zhu, Q. -S. (2006). Spin-singlet contributions to zero-field splitting of a 3d4 ion at a distorted octahedral site and applications to Cr2+ ions in Rb2CrCl4 and CrF2. Journal of Physics Condensed Matter, 18(5), 1705. doi:10.1088/0953-8984/18/5/023