1. Buchwalter, H.: Topologies, bornologies et compactologies. Thesis. Lyon 1968
2. De Wilde, M.: Perturbation of maps in locally convex spaces. Proceedings of the Analysis Conference, Rio 1972. Paris: Herman (to appear)
3. Gokhberg, I. C., Krein, M. G.: The basic propositions on defect numbers, root numbers and indices of linear operators. Am. Math. Soc. Trans. (2),13, 185?264 (1960)
4. Goldberg, S.: Unbounded linear operators (theory and applications). New York: McGraw-Hill 1966
5. Goldman, M. A., Krackovskii, S. N.: Perturbations of homomorphisms by operators of finite rank. Sov. Math. Dokl.8, 3, 670?673 (1967)