Sturesson U., Popov L., Holmer L., Basset M., Felitsyn S., Belyatsky B. Neodymium isotopic composition of Cambrian-Ordovician biogenic apatite in the Baltoscandian Basin: implications for palaeogeographical evolution and patterns of biodiversity // Geol. Mag., 2005, v. 142(4), p. 1-21.