I'm not totally sure about Perseverance Press (and am slammed for time right now and don't have time to research) and whether Janet Dawson's California Zephyr series should be considered conventionally published, but
SYKM lists the four titles, and they are pretty picky. And Dawson's other, better-known, Jeri Howard series was conventionally published, including some award nominations. (And I've liked that series.) But if you are offended by this, skip the rest of the post

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OTOH, an omnibus of the four titles is free right now at Kindle US and UK, so if you try it and hate it, you're not out any money. And I like the premise of (again per
SYKM) "a Zephyrette working on the California Zephyr between Chicago, Illinois, and the San Francisco Bay Area, in the early 1950s" as the protagonist. So I'm going to try it!
Oh yeah, titles include:
- Death Rides the Zephyr
- Death Deals a Hand
- The Ghost in Roomette Four
- Death Above the Line
Kindle US:
https://www.amazon.com/dp/B09WCTZQ7B
Kindle UK:
https://www.amazon.co.uk/dp/B09WCTZQ7B