1. Patterson R. Guidelines for auditory warning systems on civil aircraft. Civil Aviation Authority Report 82017, 1982
2. Kerr JH. Warning devices. Br J Anaesth 1985;57:696–708
3. Spatz C, Johnston JO. Basic Statistics: tales of distributions. Monterey, CA: Brooks/Cole, 1976:247
4. Fleiss, JL. Statistical methods for rates and proportions, 2d ed. New York: Wiley, 1981:126–129
5. Spatz C, Johnston JO. Basic statistics: tales of distributions. Monterey, CA: Brooks/Cole, 1976:273