US Department of Labor, Standard Industrial Classification Manual 1987… (1987 | noyear)
“ If the total value of sales for agricultural products of an establishment is less than 50 percent from a single four-digit industry, but 50 percent or more of the value of sales for its agricultural products derives from the products of two or more four-digit industries within the same three-digit industry group, the establishment is classified in the miscellaneous industry of that industry group; otherwise, it is classified as a general livestock farm in Industry 0291. ”
