“…Zinc in liver and serum was determined by the Haven (1964) neutron activation modification of the method of von Fischer and Leopoldi (1943). Serum manganese was determined by the neutron activation method of Haven, Haven, and Dunn (1966), and the tissue manganese was measured by the neutron activation procedure of Hahn, Haven, Tuma, Ogborn, and Quaife (1967).…”