Referendum Stamps - UPPER SILESIA - Fi 1-9 Stamp Series Issued by the Governing Commission of Upper Silesia
Fi 1* / Fi 2* / Fi 3* / Fi 4* / Fi 5* / Fi 6* / Fi 7** with margin / Fi 8* / Fi 9**
Reference: Fischer, “Catalog of Polish Postage Stamps (and Those Related to Poland),” Vol. II [2022 ed.], p. 192
