New here, be gentle :)

The questions should be considered in a european context.

I'm aware that most retrofit HPS lamps don't need external igniters/starters, since
they can self-ignite. What I've seen here is that they use:
1. Penning mixture with an antenna coil around the arc tube, so they ignite on mains voltage.
2. Gas starter inside, forcing ballast to generate HV pulse.
3. Snap starters (I think, not sure)

Main question is, do the lamps with starter inside (cases 2 and 3) also contain penning mixture or they use xenon like regular HPS?

I'll appreciate references to literature.

Correct, with the addition of FEC ignitors. Of the four total types, the penning-mix with antenna coil is the only one that I know of that uses a modified gas fill.

The other (non-penning) versions may also use an antenna (I know FEC ignitor lamps do, not sure about the others), but with the typical xenon fill. This is a noticeable difference, as penning-filled HPS lamps will start the characteristic neon pinkish-red, instead of the normal xenon white during warmup.

So a summary:

Penning-start:
Modified gas fill with starter antenna

Glow starter:
Shorts out the ballast temporarily for HV pulse, normal fill

Snap Switch:
Works similarly to a glow starter but supposedly more reliable, normal fill

FEC Ignitors:
Generate HV pulses electronically, normal gas fill

I don't have any references to literature sorry, but I think this is correct. Hope this helps, and welcome! I love users who ask good questions like this.

Thanks for answering.

Now I know only this specific type of retrofit HPS lamps (penning mixture) are easily recognizable by their color on startup.

The penning mixture that are used, is neon-argon.