Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Who won Women's doubles when Raina Tzvetkova won women's singles before 2000?

### Inputs:
table_name: table, columns: ['Year', "Men's singles", "Women's singles", "Men's doubles", "Women's doubles", 'Mixed doubles']

### Response:
SELECT Women's doubles FROM table WHERE Year < 2000 AND Women's singles = raina tzvetkova