"Nederland, Indexen van de Archieven, Primaire Archiefstukken (BS en DTB), 1600-2000," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:QL55-11B4 : 6 October 2017), Hendrik Johannes Mathias Pröpper in entry for Hendrikus Gerardus Marinus Wigman and Johanna Gijsberta Cornelia Emma Pröpper, Marriage 07 Aug 1929, Utrecht, Nederland; from database, openarchives (https://www.openarch.nl : 2016); citing Utrecht, archive 463, inventory number 360-03, record number 731; ; Het Utrechts Archief
