The EOS-80 seawater properties are obsolete; they have been superseded by
the International Thermodynamic Equation Of Seawater - 2010 (TEOS-10).
The official site for the thermodynamic properties of seawater is www.TEOS-10.org.
Reference
Unesco, 1983: Algorithms for computation of fundamental properties of seawater. Unesco
technical papers in marine science 44, 53pp.