Fallout in the United States and other areas, January-December 1971.
D002170:Canada; D011834:Radiation Monitoring; D011847:Radioactive Fallout / Q000032:analysis*; D013020:South America; D013325:Strontium Isotopes / Q000032:analysis; D014481:United States
D011847:Radioactive Fallout; D013325:Strontium Isotopes