Fine-structure splitting calculation in the Ar III ion: comparison of perturbative (Breit-Pauli) and non-perturbative (MCDF-EAL) predictionsV. Stancalie, V.F. Pais, A. Mihailescu and Contributors to the EFDA-TF-ITMEur. Phys. J. D, 66 3 (2012) 84DOI: https://doi.org/10.1140/epjd/e2012-20665-8