Prepn: McGookin et al., J. Soc. Chem. Ind. 59, 92 (1940); Harris et al., US 2937204 (1960 to Dow). Activity studies: Peterson, Poult. Sci. 39, 739 (1960); Joyner, Res. Vet. Sci. 1, 363 (1960). Metabolism: Smith et al., J. Agric. Food Chem. 11, 253 (1963); Smith, Anal. Biochem. 7, 461 (1964).