Mumintrollen is a 9-book series with 9 primary works first released in 1945 with contributions by Tove Jansson, David McDuff, and 5 others.
1945 • 23 Readers • 52 pages • 3.9
1948 • 8 Readers • 176 pages • 4.5
1950 • 1 Reader • 208 pages • 4
1962 • 5 Readers • 4