Alibo, D. S. and Nozaki, Y., 1999. Rare earth elements in seawater: particle association, shale-normalization and Ce oxidation. Geochim. Cosmochim. Acta 63: 363-372. 

Greaves, M. J., Rudnicki, M. and Elderfield, H., 1991. Rare earth elements in the Mediterranean Sea and mixing in the Mediteranean outflow. Earth & Planet. Sci. Lett. 103: 169-181.