Who wrote the story about Karlsson-on-the-Roof?

Explanation

Astrid Lindgren was a Swedish author, world-famous for her children's books. She started her career with the stories about Pippi Longstocking. Ronia the Robber's Daughter was her last book. Inbetween that she wrote classics such as Karlsson-on-the-Roof, Seacrow Island and the Six Bullerby Children book series.