APA (7th ed.) Citation

(1918). Keep him free: Buy War Savings Stamps issued by the United States Treasury Dept. Ketterlinus.

Chicago Style (17th ed.) Citation

Keep Him Free: Buy War Savings Stamps Issued by the United States Treasury Dept. Phila: Ketterlinus, 1918.

MLA (9th ed.) Citation

Keep Him Free: Buy War Savings Stamps Issued by the United States Treasury Dept. Ketterlinus, 1918.

Warning: These citations may not always be 100% accurate.