CREATE TABLE table_20541 ("Species" TEXT, "Indole" TEXT, "Methyl Red" TEXT, "Voges-Proskauer" TEXT, "Citrate" TEXT)

Which species show a negative result with both voges-proskauer and indole?
SELECT "Species" FROM table_20541 WHERE "Voges-Proskauer" = 'Negative' AND "Indole" = 'Negative'
SELECT "Species" FROM "table_20541" WHERE "Indole" = 'Negative' AND "Voges-Proskauer" = 'Negative'