Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_70239 ( "Stage" text, "Winner" text, "General classification" text, "Points classification" text, "Mountains classification" text, "Young rider classification" text, "Intergiro classification" text, "Trofeo Fast Team" text )

### Question ###
During which stage was the Intergiro classification held by Miguel Indurain, the Points classification held by Mario Cipollini, and the Young rider classification held by Leonardo Sierra?

### Accurate SQL ###

SELECT "Stage" FROM table_70239 WHERE "Intergiro classification" = 'miguel indurain' AND "Points classification" = 'mario cipollini' AND "Young rider classification" = 'leonardo sierra'