Footnote z

^zSee Friis et al. 2003, 2004, 2005

Friis, K., A. Körtzinger and D.W.R. Wallace. 2003. The salinity normalization of marine inorganic carbon chemistry data. Geophys. Res. Lett., 30(2):1085, doi:10.1029/2002GL015898.

Friis, K., A. Körtzinger, and D.W.R. Wallace. 2004. Spectrophotometric pH-measurement in the ocean: requirements, design and testing of an autonomous CCD-detector system. Limnology and Oceanography: Methods, 2:126-136.

Friis, K., A. Körtzinger, J. Pätsch, and D.W.R. Wallace. 2005. On the temporal increase of anthropogenic CO₂ in the subpolar North Atlantic. Deep-Sea Res. I, 51:682-691.