1935 20c lake, overprinted "Amelia Earhart Vuelo de Buena Voluntad Mexico 1935", with additional "Muestra" at bottom, upper right sheet corner margin block of four, n.h., v.f., with 1956 Philatelic Foundation Certificate, ex-George Sloane collection. Only 350 stamps were overprinted "Muestra" (making it scarcer than the issued stamp). As far as we know, this is the only known block of four (Cat No. C74S) (Image)

Est.$5,000

1936 20c lake, "Eagleman", "Secretaria de Hacienda Mexico" and lines watermark, bottom sheet block of four, n.h., well centered for issue, v.f., signed Herbert Bloch, with 1971 Friedl certificate. This is the only existing block of this elusive and popular stamp, certainly the greatest Air Post rarity from Mexico, ex-Weston collection (where it was sold in 1980 for $60,500 at Sotheby's-Parke Bennett auction in New York City) (catalogue value for singles) cat. $30000 (Cat No. C76A) (Image)

Cat. $30000, Est.$30,000

1928 (1 Oct) flown cover from Mexico City to San Francisco and again via Laredo, with U.S. franking, showing additional cachets and arrival markings on back, fine and interesting double flight (Image)

Est.$100