Johnson, Stanley R.; Lakshminarayan, P. G.; Gassman, Philip W.; Siemers, Mark; Otake, Toshitsugu; Opsomer, Jean D.; Babcock, Bruce A.; Campbell, Todd; Wu, JunJie; Mitchell, Paul D.; Bishop, Todd; Carriquiry, Alicia L.

Ames, Iowa: Center for Agriculture and Rural Development, Iowa State University, (1996)