[1] B. Arbour and D.Ž. Đoković: “On semiregular nilpotent orbits in simple Lie algebras of type D”, J. Algebra Appl., Vol. 3, (2002), pp. 341–356. http://dx.doi.org/10.1142/S0219498802000252
[2] D.Ž. Đoković: “The closure diagram for nilpotent orbits of the split real form of E 8”, CEJM, Vol. 4, (2003), pp. 573–643.
[3] T. Kimura: Introduction to prehomogeneous vector spaces, Translation of Mathematical Monographs, Vol. 215 Amer. Math. Soc., Providence, 2003.