These artifacts were found during the 1970ies in the Leudal area in southern Limburg / NL. This complex has some similarities with the Rheindahlen B-3 complex dated to Riss glaciation. I would be happy to get more information about the Mousterian in the Netherlands, because online publications in English about this topic are rare..
If you visit the old town of Leiden, please do not miss the Rijksmuseum van Oudheden. Amazing artifacts from the Maastricht Belvedere site some 250000 years old (OIS 7)!