Cover franked with 1928 3 x 5c green and 1930 35c yellow green AIR issue (SG 221 & 247) the former tied by undated SUBADMINISTRACION DE CORREOS ROBORE BOLIVIA cancel in blackish purple and the latter by undated LLOYD AEREO BOLIVIANO AGENCIA ROBORE cancel in bright red. Addressed to LA PAZ with boxed 'CORREO AEREO SANTA CRUZ' mark in red on front and large boxed 'ECONOMICE TIEMPO EMPLEANDO EL CORREO AEREO L.A.B' cachet on in red on reverse with SANTA CRUZ & COCHABAMBA transit cds's and LA PAZ arrival cds alongside with printed red on white perforated label inscribed 'MUY IMPORTANTE. Para que su correspondencia le sea devuelta en caso de no ser entregada al destinario, consigne al reverso de ella su nombre y direccion completa.' applied on reverse. A scarce early commercial airmail from one of the smaller & remote Agencies.