Experimental investigation of the hyperfine spectra of Pr I – lines: discovery of new fine structure levels with low angular momentumK. Shamim, I. Siddiqui and L. WindholzEur. Phys. J. D, 64 2-3 (2011) 209-220DOI: https://doi.org/10.1140/epjd/e2011-20250-9