Toposin

https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:4911
http://www.hmdb.ca/metabolites/HMDB0014911
http://www.genome.jp/dbget-bin/www_bget?drug:D00125
http://www.genome.jp/dbget-bin/www_bget?cpd:C01576
https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=36462
https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?sid=46505434
https://www.chemspider.com/Chemical-Structure.33510.html
http://www.bindingdb.org/bind/chemsearch/marvin/MolStructure.jsp?monomerid=50127140
https://mor.nlm.nih.gov/RxNav/search?searchBy=RXCUI&searchTerm=4179
https://www.ebi.ac.uk/chebi/searchId.do?chebiId=4911
https://www.ebi.ac.uk/chembldb/index.php/compound/inspect/CHEMBL44657
https://zinc.docking.org/substances/ZINC000003938684
http://bidd.nus.edu.sg/group/cjttd/ZFTTDDRUG.asp?ID=DAP000786
http://www.pharmgkb.org/drug/PA449552
https://www.ebi.ac.uk/pdbe-srv/pdbechem/chemicalCompound/show/EVP
http://www.rxlist.com/cgi/generic2/etopophos.htm
https://www.drugs.com/cdi/etoposide.html
https://en.wikipedia.org/wiki/Etoposide