1927 Airmail 1L on 6L , inverted surcharge, mint n.h., scarce; signed PVK and cert. Karaivanoff (1967). (Image)

1927-28 Bunavad airmails, specialized stamp assembly mounted on 12 pages, mint hinger or never hinged, noted Specimen ovpts., double perfs., colour shades, bottom sheet marginal imprints, unissued values, mixed to very fine, a lot for the specialist.

1930 (Nov 25) Registered cover to Bratislava, franked by Bunavad airmail 1L on 6L with strip of three with inverted surcharge, accompanied by a regular-surcharge example, together with other Bunavad airmail or regular values, all tied by Rousse cds's; the second largest multiple known of this famous Bulgarian variety on cover (two items are recorded bearing a block of four); a significant key item of worldwide airmails. (Image)

1931 Airmail unissued 10L in block of 4, with additional franking, used with Sofia cds on registered airmail cover from the French Legation to Sofia (printed endorsement and cachet on reverse) to Brussels, backstamped on arrival, rare; signed Field. (Image)