Electric light bulb as a symbol of light in the darkElectric light bulb as a symbol of light in the dark
The bear shows its paws in the dark, but it's still visible thereThe bear shows its paws in the dark, but it's still visible there
Excavator digs the ground against the background of dark cloudsExcavator digs the ground against the background of dark clouds
The slide rule, pencil and magnifying glass are on the notebookThe slide rule, pencil and magnifying glass are on the notebook
A picture of old books standing on a shelf on a dark backgroundA picture of old books standing on a shelf on a dark background