CREATE TABLE table_12104319_1 (womens_singles VARCHAR2, mixed_doubles VARCHAR2)

What is the womens singles of marcus ellis gabrielle white?
SELECT womens_singles FROM table_12104319_1 WHERE mixed_doubles = "Marcus Ellis Gabrielle White"
SELECT "womens_singles" FROM "table_12104319_1" WHERE "Marcus Ellis Gabrielle White" = "mixed_doubles"