CREATE TABLE table_20203 ("Ecosystem" TEXT, "Date of issue" TEXT, "Place of issue" TEXT, "No. stamps in sheet" FLOAT, "Face Value" TEXT, "Printer" TEXT)

When the face value is 42 , what was the issue's date?
SELECT "Date of issue" FROM table_20203 WHERE "Face Value" = '42¢'
SELECT "Date of issue" FROM "table_20203" WHERE "Face Value" = '42¢'