fitting van der waals law on real data

For an examples class on thermodynamics, I would like to fit Van der Waals law on data of real gasses, say $CO_2, H_2O_2, CH_4$.

I want to set out measurements of pressure and volume at constant temperature in a P-V diagram, and make a fit to determine the van der Waals parameters a and b. Only I have no idea where to look for experimental data.

Is such data available in databases or articles?

Would I have to extract them by hand from plots or are there (electronic) tables available? Any suggestion is welcome.

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Maybe these tables will be of use for your project thermo.sdsu.edu/testhome/Test/solve/basics/tables/tables.html –  anna v Dec 3 '12 at 14:59