Historic Preservation Nomination Guide
Criteria for Evaluation National Register of Historic Places
Websites of interest (alphabetical order)
Iowa Barn Foundation
National Barn Alliance
National Park Service Technical Preservation Services
National Trust for Historic Preservation
Office of the State Archeaologist
Preservation Action
Preservation Iowa
Books:
Identifying American Architecture: A Pictorial Guide to Styles and Terms, 1600-1945 by John J. G. Blumenson (Jun 1981)
Iowa's Historic Architects: A Biographical Dictionary by Wesley I. Shank.