Children's book: legendary creatures make a pact to believe in each other and thus evade extinction

[Oklennie]

Read it as a kid over thirty years ago, so the details are pretty vague. I think maybe a unicorn got killed, although I'm not terribly sure.

[Rainbowheart]

I notice your profile says you're in Germany.

Was your book in German or English?

Was it a picture book or a child's novel?

[Oklennie]

I'm not in Germany, I just use VPN.
The book was in Russian but I think it was translated from English. It was a novel.