title: Reply to the letter of L. C. Clark and G. F. Combs, Jr.
authors.forename: H D
authors.initials: HD
authors.lastname: Foster
mesh_terms: D002118:Calcium / Q000627:therapeutic use*; D002681:China; D004938:Esophageal Neoplasms / Q000453:epidemiology / Q000517:prevention & control* / Q000628:therapy; D008113:Liver Neoplasms / Q000517:prevention & control*; D012643:Selenium / Q000627:therapeutic use*
chemical_list: D012643:Selenium; D002118:Calcium