1. “Atlas of Spectral data and physical constants of organic compounds” Volume 3;Grasselli,1975
2. Remington's Pharmaceutical Sciences, 15th edition;Grasselli,1975
3. Merck Index, Ninth edition, Merck & Co., Inc., Rahaway, N.J., U.S.A., 1976, page 226
4. The United States Pharmacopeia XIX;Grasselli,1976
5. Isolation and Identification of Drugs;Clarke,1969