Its from Microwave engineering by David M Pozar.I would attach an implementation photo of such a resonator.You can see that there is no connection from the output to the input.You should give a reference where the circuit is described as "series feedback".
And why would there be a transmission line at the emitter?There should be a transmission line at the emitter.
The post#1 schematic suggests an oscillator based on negative impedance rather than external feedback.
That is called parallel feedback,not series.You can google that.DRO with the resonator in series configuration would be something like this[/url]
The DR coupled with microstrip line resonates and the transistor acts as amplifier.There I also had some doubts because I designed the output matching section for oscillation (not for stablization as in amplifier.)And yes discussing the terminology wouldn't lead anywhere.I notice that your initial post is asking "why it's called ...?" I believe, the more interesting question is "how does it oscillate?". If you understand why, you don't necessarily need to answer the first one unless you are writing a text book or preparing a lecture.