1. K. Helrich, Official Methods of Analysis, Association of Official Analytical Chemists Inc., Arlington, Virginia, USA, 1990.
2. A.I. Vogel, Textbook of Quantitative Inorganic Analysis, Longman, London, 1978.
3. NDC Infrared Engineering, Tobacco Applications: http://www.ndcinfrared.com/applications/tobacco/tobacco.html.
4. Personal Contacts: NDC Infrared Engineering.
5. Epsilon Industrial Inc. Guided Microwave Spectroscopy Series Analyser Instruction Manual, 1996.