"Nederland, Indexen van de Archieven, Primaire Archiefstukken (BS en DTB), 1600-2000," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:QL5L-FDS6 : 6 October 2017), Theodor Heijckmann and Mechtilda Verhoeven, Marriage 07 Jan 1867, Huissen, Gelderland, Nederland; from database, openarchives (https://www.openarch.nl : 2016); citing Huissen, archive 0207, inventory number 4031, record number 1; ; Gelders Archief.
"Nederland, Indexen van de Archieven, Primaire Archiefstukken (BS en DTB), 1600-2000," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:QL5L-LWM6 : 6 October 2017), Theodor Heijckmann and Francina Arts, Marriage 07 Jun 1899, Huissen, Gelderland, Nederland; from database, openarchives (https://www.openarch.nl : 2016); citing Huissen, archive 0207, inventory number 4027, record number 25; ; Gelders Archief.
"Nederland, Indexen van de Archieven, Primaire Archiefstukken (BS en DTB), 1600-2000," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:QLN4-9DWG : 30 August 2017), Theodor Heijckmann, Death 11 Feb 1912, Huissen, Gelderland, Nederland; from database, openarchives (https://www.openarch.nl : 2016); citing Huissen, archive 0207, inventory number 8453, record number 10; ; Gelders Archief.
"Deutschland Geburten und Taufen, 1558-1898", database, FamilySearch (https://familysearch.org/ark:/61903/1:1:NZLW-396 : 25 February 2020), Theodor Heyckmann, 1835.
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