Hoffman, Walter E., Merryweather, Algernon (1848). 36N 20W - Survey Map of Gull Island, St. Martin Island and Gravel Island, Fairbanks Township, Delta County, Page 1 [Michigan]. Department of Natural Resources. https://michigan.access.preservica.com/uncategorized/IO_ea597667-a1fb-4f46-b43d-9cc20c2099a1 (map)