With recent reports linking high blood levels of lead to juvenile delinquency, the lead story grows. In our May 15 issue we ran a number of letters commenting on Jamie Lincoln Kitman's "The Secret History of Lead" [March 20]. Additional communications since then prompt a further editorial comment. The original lengthy manuscript contained footnotes, scrupulously documenting the sources of all quotations, facts, analyses. These were used for fact-checking, but as an editorial decision these citations were omitted from the published article for reasons of style and length, although the names of primary sources consulted were listed in the author's note. The editors regret the omission of the full citations to the articles from which Kitman drew important information and would like to give credit to those authors and articles and enable those interested to read them. Kitman joins us in gratefully acknowledging the pathbreaking work that preceded his article. Of particular value in providing archival material was David Rosner and Gerald Markowitz, "A 'Gift of God?' The Public Health Controversy Over Leaded Gasoline During the 1920s," American Journal of Public Health, April 1985. We also single out articles and papers by Alan P. Loeb on "Sloanism," Ethyl's divestments and the Kehoe rule: "Birth of the Kettering Doctrine: Fordism, Sloanism and the Discovery of Tetraethyl Lead," Business and Economic History, Fall 1995; "Surmountable Obstacles to the Adoption of Emissions Trading Programs: The Historical Perspective"; and "Birth of the Kehoe Rule: Implications of the Surgeon General's Review of Tetraethyl Lead, 1925-1926." Special thanks also to the following authors: William Kovarik, "Henry Ford, Charles Kettering and the 'Fuel of the Future,'" Automotive History Review, Spring 1998; William Graebner, "Hegemony Through Science: Information Engineering and Lead Toxicology, 1925-1965," in David Rosner and Gerald Markowitz, eds., Dying for Work: Workers' Safety and Health in Twentieth-Century America, Indiana University Press, 1989. Jerome O. Nriagu, "Clair Patterson and Robert Kehoe's Paradigm of 'Show Me the Data' on Environmental Lead Poisoning." Jerome O. Nriagu, "Automotive Lead Pollution: Clair Patterson's Role in Stopping It," in Cliff Davidson, ed., Clean Hands: Clair Patterson's Crusade Against Environmental Lead Contamination, Nova Science Publishers, 1999. H.L. Needleman, "Clair Patterson and Robert Kehoe: Two Points of View of Lead Toxicity," Environmental Research, Section A, 1998. George B. Kauffman, "Midgley: Saint or Serpent?" Chemtech, December 1989.