With the help of encyclopediadubuque.org
http://www.encyclopediadubuque.org/index.php?title=HOFFMANN,_Albert_J.
http://www.encyclopediadubuque.org/index.php?title=SINGER_MANUFACTURING_COMPANY
http://www.encyclopediadubuque.org/index.php?title=P._HUGHES_AND_SON
http://www.encyclopediadubuque.org/index.php?title=DUBUQUE_TURBINE_AND_ROLLER_MILL_COMPANY_(THE)