1. Abeasis, S., Del Fra, A.: Degenerations for the representations of an equioriented quiver of type $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{A} _m$$ . Boll. Un. Mat. It. (Suppl.) Algebra e Geometria, 157–171 (1980)
2. Gabriel, P.: Unzerlegbare Darstellungen. I. manuscripta math.6, 71–103 (1972)
3. Gabriel, P.: Indecomposable representations. II. Ist. Nazionale di Alta Mat. Symposia Mat.XI, 81–104 (1973)
4. Grothendieck, A., Dieudonné, J.: EGA O-IV. Publ. Math. de l'I.H.E.S.11, 20, 24, 28, 32, Paris (1961–1967)
5. Hesselink, W.: Singularities in the nilpotent scheme of a classical group. Trans. Am. Math. Soc.222, 1–32 (1976)