The list of eBay examples has a lot that I would not consider for a Victrola from the period of yours. Different strokes, and all that, I suppose.
I would not play any electrically recorded 78 on a 1909 Victrola. For guidance, a few tips, not close to exhaustive, that *I'd* suggest would be these:
Any Victor record made by the Victor Talking Machine Company *unless* it has a VE in an oval in the deadwax (area between grooves and label). VE marks it as electrically recorded. Most have the so-called "scroll" label (like the one here
http://www.denvernightingale.com/labels/vic26.html), but during the transition period some had the earlier "batwings" style that normally would be acoustic. VE is an infallible guide, because Victor was required so to mark and pay a royalty for all records made with its licensed Western Electric recording process.
Any Columbia record with the word "graphophone" on the label.
Any red-colored Vocalion. Any Brunswick that has a black and white, green and white, or gold and white label with a red shield.
Lyric by Lyrophone *unless* it's vertical cut, but vertical Lyrics are sufficiently uncommon that you're unlikely to stumble on one unbeknownst.
Little Wonder.
Any Opera Disc. Any Operaphone.
I *think* you're safe with any Harmony. OKeh not referencing CBS or showing hints of electric recording is probably also--well, OK. Again, some of the very early ones were vertical cut, but again those are uncommon.
No Victor referencing RCA on the label. No Columbia or OKeh referencing CBS. No Columbia having the words "Viva Tonal" on the label. None from these houses with a little W in a circle in the deadwax--Columbia's equivalent of Victor's VE.
No Edison. No Pathé except those marked as Actuelle. (You'll actually destroy the other Pathé acoustics if you try to play them with steel needles, and as vertical cut records they will give you no or next to no musical sound on a Victrola.) No Rishell. No Rex that references sapphire on the label; these had the Pathé cut.
No Decca. No Mercury.
If an off-brand label has an E in a circle on the label, chances are it's electric and too late for your purposes. Of course, if it references "electric recording," that's all you need to know.
The foregoing is all for US labels, and it's far, far from a complete list of things that are suitable for a 1909 L-door Victrola. Lots of little off labels purveying dance or other popular music came and went during or partially during the acoustic era. Foreign, particularly English, disks are a whole other bag of cats, and I'll leave it to our friends in the UK to sort those out.