1931 Mexico Newer & B/B Covers

5930- 1918, CANANEA, SONORA TO NOGALES, WITH BACK STAMP, 5¢ POSTAGE DUE USED AS POSTAGE. NO BACK FLAP

5932- 1915, – TO CERRALVO, N.L.,POSTAGE DUE, REVOLUTIONARY OVERPRINT ON 1¢ & 4¢

5945- 1920, REGISTERED FROM MEXICO TO GERMANY

5934- 1914, #386, WITH POSTAGE DUE 2¢ PAID, WITH #385, TO NOGALES

5950- 1935, PORT OF CALL, MAZATLAN, U.S.S. WORDEN