1. Merriam-Webster Collegiate Dictionary (1998), Springfield, MA: Merriam-Webster.
2. Microsoft Encarta College Dictionary (2001), New York, NY: St. Martin's Press.
3. New Oxford American Dictionary (2001), Oxford, UK: Oxford University Press.
4. Newbury House Dictionary of American English, (1999), Boston, MA: Heinle & Heinle Publishers
5. Oxford Advanced Learners' Dictionary (2003), Oxford, UK: Oxford University Press.