 | Archived from the original on 2015-04-02. Retrieved 2023-09-17. "Sigmaplan". www.sigmaplan.be. Retrieved 2023-09-21. "Scheldemug voorlopig afgeremd". De... 7 KB (843 words) - 20:17, 14 December 2023 |
 | Appeal Democrat, Retrieved on August 12, 2009 http://www.sigmaplan.be/nl/sigmaplan/hoe-is-het-sigmaplan-ontstaan Archived 2015-09-16 at the Wayback Machine... 16 KB (2,189 words) - 15:15, 13 February 2024 |
 | Standaard (in Flemish). Retrieved 9 May 2012. "Hoe is het Sigmaplan ontstaan?" (in Flemish). Sigmaplan. Archived from the original on 5 October 2013. Retrieved... 117 KB (4,053 words) - 19:37, 23 April 2024 |
 | tide) with a nature development function. In the framework of the Belgian Sigmaplan, aimed at protecting the whole river basin against floods, more areas... 2 KB (280 words) - 08:51, 20 February 2024 |
of Hedwigepolder was proposed. In Flanders, where people worked on the Sigmaplan [nl], they proposed the depoldering of part of the Prosperpolder [nl]... 12 KB (1,207 words) - 00:01, 24 January 2023 |