Ref.: Chaussidon, M. and Appel, P.W.U. (1997) Boron isotopic composition of tourmalines from the 3.8 Ga-old Isua supracrustals, West Greenland: implications on the δ11B value of early Archean seawater. Chem. Geol.: 136: 171-180.
Dymek, Brothers, and Schiffries, 1988: Journal of Petrology 29(6):153-1397.