"Postcodetool for 2441LE". Actueel Hoogtebestand Nederland (به هلندی). Het Waterschapshuis. Archived from the original on 7 January 2019. Retrieved 16 August 2013.
"College van B&W" [Board of mayor and aldermen] (به هلندی). Gemeente Nieuwkoop. Archived from the original on 31 October 2013. Retrieved 16 August 2013.
web.archive.org
"College van B&W" [Board of mayor and aldermen] (به هلندی). Gemeente Nieuwkoop. Archived from the original on 31 October 2013. Retrieved 16 August 2013.
"Postcodetool for 2441LE". Actueel Hoogtebestand Nederland (به هلندی). Het Waterschapshuis. Archived from the original on 7 January 2019. Retrieved 16 August 2013.