1. Accident facts 1988 . (1988). National Safety Council Chicago Ill. 32–44.
2. Altayeb S. A. (1990). “Drug testing and its impact on the incident rate in the construction industry ” PhD dissertation Clemson Univ. Clemson S.C.
3. Employee drug screening: Detection of drug use by urinalysis (questions and answers) . (1988). US Dept. of Health and Human Services Nat. Inst. on Drug Abuse Washington D.C.
4. Hoffer W. (1986). “Business' war on drugs.” Nation's Business (Oct.) 19.
5. Maloney W. F. (1987). Substance abuse: The problem and its solution . Construction Industry Inst. Austin Tex.