Sources to look at

Joachim Köppen Kiel/Strasbourg/Illkirch Spring 2007

The daylight sky or the Sun (through diffusor)

Incandescent lamps

The blueish mercury vapour street lamps

The orange sodium vapour street lamps

Advertisement signs ("Neon" lamps, gas discharge lamps)

Fluorescent tubes

the reddish-orange glowing lamps used as night lamps, also found as indicators of electrical equipment (discharge of helium/neon gas)

Light emitting diodes (LED) found in electrical equipment, signals, and traffic lights

Electricity-saver bulbs

Green displays of some electrical clocks

and anything else ...

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