Prepcat

http://classyfire.wishartlab.com/tax_nodes/C0000001
http://classyfire.wishartlab.com/tax_nodes/C0000424
http://classyfire.wishartlab.com/tax_nodes/C0000446
http://classyfire.wishartlab.com/tax_nodes/C0000699
http://classyfire.wishartlab.com/tax_nodes/C0000699
http://classyfire.wishartlab.com/tax_nodes/C0003866
http://classyfire.wishartlab.com/tax_nodes/C0003944
https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=24414
https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?sid=347827920
https://www.chemspider.com/Chemical-Structure.22823.html
https://mor.nlm.nih.gov/RxNav/search?searchBy=RXCUI&searchTerm=1331
https://www.ebi.ac.uk/chebi/searchId.do?chebiId=133326
https://www.ebi.ac.uk/chembldb/index.php/compound/inspect/CHEMBL2105897
https://en.wikipedia.org/wiki/Barium_sulfate