The following links are from Dan Hudson, Michigan State University Extension.

Table 1-29. Estimated Risks to Grain Corn Yield and Quality From
Late-Season Frost Damage
http://www.omafra.gov.on.ca/english/crops/pub811/1other.htm#table1-29

Guidelines for Handling Corn Damaged by Frost Prior to Grain Maturity
http://corn.agronomy.wisc.edu/WCM/W156.aspx

Potential Yield Losses in Corn From Fall Frost Damage
http://www.ces.purdue.edu/extmedia/CL/CL-9.pdf

Assessing Frost Damage in Soybeans
http://www.ag.ndsu.edu/disaster/winterstorm/frostsoybeans.html

Ontario perspective on soybeans damaged by frost

http://www.omafra.gov.on.ca/english/crops/pub811/2other.htm