<http://schema.org/thumbnailUrl>
<https://drscdn.500px.org/photo/18840899/w%3D160_h%3D160_s%3D1/0bd9292ef025ad726fdcd67e3a5990ed>
<https://marketplace.500px.com/photos/18840899/bl%25C3%25A4tterwiese-by-pia-nitzsche>