The sources are:

Symbol
$b_{\mathrm{VdW}}$
Unit
L/mol
Used in
$p_{\mathrm{VdW}}$
Choices
GasFormulab
Air-0.0364
N2N20.0387
SF6SF60.08786
CO2CO20.04286
COCO0.03948
O2O20.03186
H2H20.02651
NH3NH30.03713
SO2SO20.05679
HeHe0.0238
ArAr0.03201
KrKr0.0396
XeXe0.05156