D. Zimmerman, P. Zimmerman, G. Aepfelbach, A. Kuhnert, Isotope shift and hyperfine structure of the transition 5d6s2D3/2-5d6s6p4F3/2 of 175Lu and 176Lu, doi:10.1007/BF01412940, Z. Phys. A 295, 307-310, 1980