<http://schema.org/thumbnailUrl>
<https://drscdn.500px.org/photo/24731171/w%3D160_h%3D160_s%3D1/4dfbfad9d1d59e2ef1151d596e6d786d>
<https://marketplace.500px.com/photos/24731171/faces-of-tibet-3-by-sk-teh>