Allrakäraste syster (Swedish)

"""Now I'll tell you a secret: I have a twin sister. Don't tell anyone about it! Her name is Ylva-Li, and she calls me "Dearest sister". Ylva-Li only likes me. We have a special language , which we just understand. And we have so much fun together."The story Allrakäraste syster from the collection Nils Karlsson-Pyssling published as a picture book with illustrations by Hans Arnold."