With the discovery of soybean cyst nematode (SCN) in the U.S. in 1954, the research for resistance was initiated. Ross and Brim (1957) identified several soybean plant introductions resistant to the North Carolina SCN populations. Epps and Hartwig (1972) reported PI lines resistant to race 4.
Rao, A. P. and Anand, S. C.
"Research Notes : United States : Screening for cytoplasmic/maternal effects in resistance to soybean cyst nematode,"
Soybean Genetics Newsletter: Vol. 13
, Article 29.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol13/iss1/29