Histidine

https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:15971
http://www.genome.jp/dbget-bin/www_bget?cpd:C00135
http://www.hmdb.ca/metabolites/HMDB0000177
http://www.genome.jp/dbget-bin/www_bget?drug:D00032
http://www.genome.jp/dbget-bin/www_bget?cpd:C00135
https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=6274
https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?sid=46507001
https://www.chemspider.com/Chemical-Structure.6038.html
http://www.bindingdb.org/bind/chemsearch/marvin/MolStructure.jsp?monomerid=7953
https://mor.nlm.nih.gov/RxNav/search?searchBy=RXCUI&searchTerm=5340
https://www.ebi.ac.uk/chebi/searchId.do?chebiId=15971
https://www.ebi.ac.uk/chembldb/index.php/compound/inspect/CHEMBL17962
https://zinc.docking.org/substances/ZINC000006661227
http://www.pharmgkb.org/drug/PA449882
http://www.guidetopharmacology.org/GRAC/LigandDisplayForward?ligandId=3310
https://www.ebi.ac.uk/pdbe-srv/pdbechem/chemicalCompound/show/HIS
http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/lhi_0137.shtml
https://en.wikipedia.org/wiki/Histidine