I found some great children’s stories on a Russian website. I would like to share them, but I am completely unaware if they are public domain or not and I don’t want to get in trouble.
There needs to be either an explicit dedication to the public domain by the author, or a known age that qualifies them for the public domain.
Note that just because they’re old stories doesn’t mean that the versions you found are that old. I could write my own version of Rumpelstiltskin (having told it hundreds of times to my son), but it would end up being my version of a retelling to which I would own copyright, never mind the fact that the original story is old beyond the reach of copyright.
Edit: But nothing ought to prevent you from posting the link to them here, even if you decide you cannot upload them into Lingq lessons.
Edit 2: This might help you decide: Template:PD-Russia - Wikimedia Commons