Postal Service of the 1st Polish Corps under Gen. Dowbór-Muśnicki, Fi 12A–15A ** stamp series, 2nd reprint edition
Fi 12 A**, no backing paper, MIKSTEIN guarantee and one additional illegible signature (Brajer?)
Fi 13a A** [yellow], perforated, no gum, MIKSTEIN guarantee, KRÜGER
Fi 14 A**, perforated, no backing paper, MIKSTEIN guarantee, and one more illegible signature (Brajer?)
Fi 15 A**, perforated, MIKSTEIN guarantee
Reference: Fischer, “Catalog of Polish Postage Stamps (and Those Related to Poland),” Vol. II [2022 ed.], p. 34
