Gotta love Amazon recommendations. Apparently, it found out due to my viewing history, that I am interested in stem vowels:
What they did not explain is how the Belgium they came up with that (I know for a fact that I did not search for that), and more importantly, how it is even possible to develop an interest in stem vowels.
Then again, I am not a linguist, so maybe I am just an utter philistine when it comes to the beauty of stem vowels. Who knows?