Table schema:
CREATE TABLE table_15635768_1 (no_stamps_in_sheet VARCHAR, face_value VARCHAR, printer VARCHAR)

Question: How many stamps have a face value of 37¢ and were printed in the banknote corporation of america?
SQL: SELECT COUNT(no_stamps_in_sheet) FROM table_15635768_1 WHERE face_value = "37¢" AND printer = "Banknote Corporation of America"