Poole WK, Pollack M, Rapoport I, Williams V, Koch MA, Rao AV, Bartel DA. Use of Multivariate Methods in Quantifying the Variability in the Perception of Neonatal Intensive Care Unit Characteristics in Nine Hospitals in the Washington, DC Area: the NIH-DC Initiative to Reduce Infant Mortality in Minority Populations in the District of Columbia. Interstat. 2002 Jan 1.
Glass RL, Rothman KJ, Espinal F, Velez H, Smith NJ. Prevalence of human dental caries and water-borne trace metals. Arch Oral Biol. 1973 Sep;18(9):1099-104. doi: 10.1016/0003-9969(73)90083-6