CREATE TABLE table_15635768_1 (date_of_issue VARCHAR2, face_value VARCHAR2)

When the face value is 42 , what was the issue's date?
SELECT date_of_issue FROM table_15635768_1 WHERE face_value = "42¢"
SELECT "date_of_issue" FROM "table_15635768_1" WHERE "42¢" = "face_value"