I got today a M39 L39 to Sony E mount adapter for my first digital camera, which I bought 9 years ago, which was getting dusty. Time to look at it again, a descendant of it is in the cards.
Seen here with a Russian 50mm f2 Jupiter lens. However, the 35mm Jupiter did not fit the camera, as the back element stand out too much. I will look on the web for alternatives.