CREATE TABLE table_18415 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

What district is incumbent elmer j. holland from?
SELECT "District" FROM table_18415 WHERE "Incumbent" = 'Elmer J. Holland'
SELECT "District" FROM "table_18415" WHERE "Incumbent" = 'Elmer J. Holland'