M. J. Evans and M. H. Kaufman :Establishment in culture of pluripotential cells from mouse embryos. Nature, 202 (1981) 154
G. R. Martin: Isolation of a pluripotent cell line from earlymouse embryos cultured in medium conditioned by teretocarcinoma stem cell, Proc. Natl. Acad. Sci. U S A., 78 (1981) 7634