CREATE TABLE table_name_33 (launched VARCHAR, commissioned VARCHAR, bow_number VARCHAR)

When did the ship commissioned in November 1975 with a bow number of ps-18 launch?
SELECT launched FROM table_name_33 WHERE commissioned = "november 1975" AND bow_number = "ps-18"
SELECT "launched" FROM "table_name_33" WHERE "bow_number" = "ps-18" AND "commissioned" = "november 1975"