7Veatch A E, Brockman J D, Spate V L, et al. Selenium and nutrition: the accuracy and variability of the selenium content in commercial supplements [J]. Journal of Radioanalytical and Nuclear Chemistry, 2005,264 ( 1 ) : 33-- 38.
8Gordon M E, Edwards M S, Sweeney C R, et al. Effects of added chelated trace minerals, organic selenium, yeast culture, direct-fed microbials, and Yucca schidigera extract in horses: II. Nutrient excretion and potential environmental impact [J]. Journal of Animal Science, 2013,91 ( 8 ) : 3909- 3916.
