Grupa was a private village within the Polish Crown, owned by various Polish nobles, incl. the Kopycki and Żelisławski families, administratively located in the Świecie County in the Pomeranian Voivodeship.[2]
^Biskup, Marian; Tomczak, Andrzej (1955). Mapy województwa pomorskiego w drugiej połowie XVI w. (in Polish). Toruń. pp. 106–107.{{cite book}}: CS1 maint: location missing publisher (link)
^Wardzyńska, Maria (2009). Był rok 1939. Operacja niemieckiej policji bezpieczeństwa w Polsce. Intelligenzaktion (in Polish). Warsaw: IPN. pp. 167, 184.