Coming in August from the University of Wisconsin Press:
James P. Leary, Folksongs of Another America, Field Recordings from the Upper Midwest, 1937–1946
Most of the material appears to be from Wisconsin, but there is probably Minnesota material as well.
Available at uwpress.wisc.edu/books/5231.htm
Thanks for posting info on my Folksongs of Another America project. It does include MN recordings: Serbs from Eveleth, a Scots Gaelic singer from Duluth, and Finns from Winton, Ely, Cloquet, etc. There are also lots of recordings from the Upper Peninsula of MI, besides the WI recordings. Wish there was more from MN, but only a few field recordings were made there by Sidney Robertson during the 1937-1946 period I focused on. — Jim Leary
Marjorie Edgar also collected in that period, collaborating with Sidney Robertson for a time, but she was only interested in Finnish material. And it has all been published — and I for one don’t understand a word of it anyway. :-)
Good luck with the book; it really does sound like an impressive work.