Some images on the website are used under some Creative Commons licenses.
Author attributions:
https://www.flickr.com/photos/giuseppemilo/
https://www.flickr.com/photos/paulslab/
https://www.flickr.com/photos/thomashawk/
https://www.flickr.com/photos/daniel-wehner/
https://www.flickr.com/photos/fensterbme/
https://www.flickr.com/photos/paulslab/
https://www.flickr.com/photos/thomashawk/
https://www.flickr.com/photos/daniel-wehner/
https://www.flickr.com/photos/fensterbme/