The website below is for a Gull Lake history book "From Prairie Trails to Pavement" Go to page 83 and 84 for the William Christiansen story and to page 545 for Peter and John Peterson. The Petersons shown may not be the right ones but it is all that is there. You can look at the whole book by using the web page keys.
The town of "Gull Lake Memories" history book also has a story on Bill Christiansen but it is the same as this one.
Good luck with your research.