*[http://www.acadsoft.co.uk/scdbase/scdbase.htm IUPAC SC-Database]  A comprehensive database of published data on equilibrium constants of metal complexes and ligands
*[https://www.nist.gov/ts/msd/srd/nist46.cfm NIST Standard Reference Database 46] : Critically selected stability constants of metal complexes
*[https://web.archive.org/web/20081009060809/http://www.chem.wisc.edu/areas/reich/pkatable/ Inorganic and organic acids and bases] pK data in water and DMSO
*[https://web.archive.org/web/20060928231137/http://www.grc.nasa.gov/WWW/CEAWeb/ceaHome.htm NASA Glenn Thermodynamic Database webpage with links to (self-consistent) temperature-dependent specific heat, enthalpy, and entropy for elements and molecules]