The site that sells lacto fermented juice of the soft inside of linden tree/lime tree (in boxes of small individual doses/vials) is below. They also sell fermented black radish juice as you can see:
Natalia, I just emailed the site that sells organic fermented beets, carrots, black radish, cabbage etc. I am waiting for their answer. Please note that, contrary to what I mentioned, they sell the beet in chunks, not in juice, but you can turn it into juice easily just by running it thru the blender. Or you can eat the chunks in salads--its very good with potato salad, or a green salad.
I have another address that sells beet juice, I will give it to you as well.