MXL

https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:17303
http://www.genome.jp/dbget-bin/www_bget?cpd:C01516
http://www.hmdb.ca/metabolites/HMDB0014440
http://www.genome.jp/dbget-bin/www_bget?drug:D08233
http://www.genome.jp/dbget-bin/www_bget?cpd:C01516
https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=5288826
https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?sid=46505161
https://www.chemspider.com/Chemical-Structure.4450907.html
http://www.bindingdb.org/bind/chemsearch/marvin/MolStructure.jsp?monomerid=50000092
https://mor.nlm.nih.gov/RxNav/search?searchBy=RXCUI&searchTerm=7052
https://www.ebi.ac.uk/chebi/searchId.do?chebiId=17303
https://www.ebi.ac.uk/chembldb/index.php/compound/inspect/CHEMBL70
https://zinc.docking.org/substances/ZINC000003812983
http://bidd.nus.edu.sg/group/cjttd/ZFTTDDRUG.asp?ID=DAP000071
http://www.pharmgkb.org/drug/PA450550
https://www.ebi.ac.uk/pdbe-srv/pdbechem/chemicalCompound/show/MOI
http://www.rxlist.com/cgi/generic/ms.htm
https://www.drugs.com/morphine.html
http://www.pdrhealth.com/drug_info/rxdrugprofiles/drugs/msc1277.shtml
https://en.wikipedia.org/wiki/Morphine