CREATE TABLE table_36705 ("Year" FLOAT, "Men's singles" CLOB, "Women's singles" CLOB, "Men's doubles" CLOB, "Women's doubles" CLOB, "Mixed doubles" CLOB)

Who won Women's doubles when Raina Tzvetkova won women's singles before 2000?
SELECT "Women's doubles" FROM table_36705 WHERE "Year" < '2000' AND "Women's singles" = 'raina tzvetkova'
SELECT "Women's doubles" FROM "table_36705" WHERE "Women's singles" = 'raina tzvetkova' AND "Year" < '2000'