McArthur, J.M.; Howarth, R.J.; Bailey, T.R.; (2001) Strontium isotope stratigraphy: LOWESS version 3: best fit to the marine Sr-isotope curve for 0-509 Ma and accompanying look-up table for deriving numerical age. The Journal of Geology , 109 (2) pp. 155-170. 10.1086/319243. Green open access