A September 15, 1937 commercial airmail cover from W. Francisco Siebold (Servicio Para Autos), Guatemala City, Guatemala, franked with a pair of 1c olive definitives, a 30c red 'Exterior' airmail stamp depicting a bird in flight, and a pair of 3c red-and-green stamps — all tied by a violet 'Correo Internacional' circular datestamp and machine wavy-line cancel — addressed to Gibson Co., Indianapolis, Indiana, USA, with a bold blue diagonal 'Correo Aereo' airmail label stripe; cover shows light age toning and minor wrinkling consistent with its 88 years, no tears or significant faults. Please review the scans for condition.