1920 10c green (Pilot Watching Plane), unfolded and intact sheet of 72, unused without gum as issued, v.f., cat. $4320 (Cat No. C11) (Image)

Cat. $4320, Est.$500

1920 10c red brown, unfolded and intact se-tenant sheet of 68, bottom row of eight printed sideways, creating tete-beche combinations (at least six pairs), also "C. Valiente" imprint, unused without gum as issued, faint toning at left, irregularly cut but clear at sides, fine and rare sheet (tete-beche pairs catalogue $1,000 each, single stamps $65 each) cat. $9445 (Cat No. C11C-D) (Image)

Cat. $9445, Est.$2,000

1920-21 Sociedad Colombo-Alemana de Transportes Aereos (SCADTA), 10c yellow, 15c blue (part of print and turn tete-beche showing at bottom) and 30c rose (panes of 32), also 30c black on rose and 50c green (sheets of 48), last two folded between stamps, with hinge reinforcements, creases and stains, otherwise fine-v.f., quite possibly the only surviving set of sheets, ex-Matthews, Braunstein and Debby Friedman collections, cat. $10240 (Cat No. C12-16) (Image)

Cat. $10240, Est.$2,500

1920 10c on 50c green, used with additional franking on flown cover from Neiva to Bogota, oval "Sociedad Colombo Allemand Correos Aereos Girardot" and "Navegacion Aerea Neiva" markings on back, signed Schoendorf, with 2018 APS certificate (catalogued as used off cover) cat. $825 (Cat No. C18) (Image)

Cat. $825, Est.$250