1. Bassuk, N.L. 1986. Reducing Pb uptake in lettuce.Horticultural Science,21, 993–995.
2. Boggess, S.F., Hassett, J.J. and Koeppe, D.E. 1978. Effect of soil phosphorus fertility level on the uptake of cadmium by maize.Environmental Pollution,15, 265–270.
3. Bornschein, R.L., Succop, P.A., Krafft, K.M., Clark, C.S., Peace, B. and Hammond, P.B. 1986. Exterior surface dust lead, interior house dust lead, and childhood lead exposure in an urban environment.Trace Substances and Environmental Health,20, 322–332.
4. Butterfield, B.W. 1988.National Gardening Survey. National Gardening Association Inc., Burlington, VT.
5. Calabrese, E.J., Barnes, R., Stanek, E.J., III, Pastides, H., Gilbert, C.E., Veneman, P., Wang, X., Lasztity, A. and Kostecki, P.T. 1989. How much soil do young children ingest: an epidemiologic study.Regulatory Toxicology and Pharmacology,10, 123–137.