<http://schema.org/thumbnailUrl>
<https://drscdn.500px.org/photo/19313977/w%3D160_h%3D160_s%3D1/5deb4fec330d4e378a2bcfde577eec9f>
<https://marketplace.500px.com/photos/19313977/lake-walchensee-by-hartmut-albert>