Clarify license of original images

Hello Andrea,

I'm having a deeper look into your images.

It seems that you also imported images that were linked to from OSM.

For example: https://www.openstreetmap.org/node/10992904932 and https://www.openstreetmap.org/node/11357413791 both link an image.

Those link to https://bookcorners.org/library/dalfsen-middeleeuwen/ and https://bookcorners.org/library/rotterdam-jongkindstraat , where you show those images as well. THose images are hosted on your server.

My question is:

- Did you have permission to copy all those images onto your own server?
- By having a 'contributor agreement' stating this, this gives the impression that all the images on your website are CC-BY-SA 4.0. Is this an correct assumption?
- If this is the case, do you have permission to republish all those images as CC-BY-SA 4.0. ?