1. Preservation of sub-p.p.b. levels of mercury in distilled and natural fresh waters
2. Interlaboratory Quality Control Study No. 16;Aspila,1978
3. H. Agemian and A.S.Y. Chau, Interlaboratory Quality Control Study No. 24, Eight Phenoxy Acid Herbicides in Fresh Natural Water, Report Series, Inland Waters Directorate, Water Quality Branch, Ontario Region, in press.