Burt, William (Surveyor), Burt, William Austin, 1792-1858, Higgins, Sylvester W. (1847). 50N 38W - Survey Map of Greenland Township, Ontonagon County [Michigan]. Department of Natural Resources. https://michigan.access.preservica.com/uncategorized/IO_86a12250-246e-4e45-aaf5-f02813971ebc (map)