CREATE TABLE table_9726 ("Tournament" CLOB, "Surface" CLOB, "Week" CLOB, "Winner" CLOB, "Finalist" CLOB, "Semi finalists" CLOB)

Which Semi finalists had a Week of may 15?
SELECT "Semi finalists" FROM table_9726 WHERE "Week" = 'may 15'
SELECT "Semi finalists" FROM "table_9726" WHERE "Week" = 'may 15'