Herman D. White was president of the Northern League from 1935-1957 and from 1961-1962. He wrote a short document called "An Informal History of the Northern Baseball League," which, after White's death in 1976, passed to Walter H. Brovald, his nephew. Brovald acted as editor of White's history, and, setting the type himself, published the document in 1982.
The original document took the form of a booklet about 20 pages long. It is available here online.