1. Sweetman S. C. , Ed., Martindale, The Complete Drug Reference, 33 rd ed., Pharmaceutical Press, London, (2002), p. 89.
2. British Pharmacopoeia, Her Majesty's Stationary Office, London (2003), p. 1868, A136–A137.
3. European Pharmacopoeia, Council of Europe, 6th ed., Strasbourg (2008), p. 3104–3105.
4. Kinetic spectrophotometric determination of tramadol hydrochloride in pharmaceutical formulation