Registered airmail cover franked with 1924 10c black & orange red, 25c black & blue and 1b black & red brown 'Establishment of National Aviation School' issue plus 1927 1b scarlet, 1930 10c vermilion, 1931 50c bright magenta, 1933 5c on 1b scarlet and 1933 2c green, 5c dull blue, 15c purple & 25c indigo (SG 170, 172, 174, 202, 255, 264, 273, 278/279 & 281/282) all tied by multiple strikes of the LA PAZ 'CHACO WAR' slogan cancel & cds in purple dated 11 JAN 1935 with boxed registration marking also on front, Addressed to GERMANY with transit & arrival marks on reverse. A very fine & attractive franking including the 1924 1b which is very difficult to find used on cover.