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 ...