api_id,name,source
1,PubChem (compound),https://pubchem.ncbi.nlm.nih.gov/
2,PubChem (substance),https://pubchem.ncbi.nlm.nih.gov/
3,CAS Common Chemistry,https://commonchemistry.cas.org/
4,Computational Toxicology and Exposure Data,https://api-ccte.epa.gov/docs/
5,NCI/CADD Chemical Identifier Resolver,https://cactus.nci.nih.gov/chemical/structure/
6,ChemSpider,https://www.chemspider.com/