1. FDA, Tainted products marketed as dietary supplements, 2010. http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm236774.htm.
2. Outbreak of hypoglycaemia: sexual enhancement products containing oral hypoglycaemic agent;Poon;Hong Kong Med. J.,2009
3. Medsafe, Health product alert INV10019, 2010. http://www.medsafe.govt.nz/.
4. Safety assessment of esters of p-hydroxybenzoic acid (parabens);Soni;Food Chem. Toxicol.,2005
5. The discovery of tadalafil: a novel and highly selective PDE5 inhibitor. 2: 2,3,6,7,12,12a-hexahydropyrazino[1′,2′:1,6]pyrido[3,4-b]indole-1,4-dione analogues;Daugan;J. Med. Chem.,2003