Burt, William Austin, 1792-1858, Clason, Lewis, Mullett, James H. (1838). 21N 06E - Survey Map of Sherman Township, Iosco County [Michigan]. Department of Natural Resources. https://michigan.access.preservica.com/uncategorized/IO_1dcf010e-866e-4d1b-b826-6256c21f1640 (map)