Some Metric Aspects of the Open Mapping and Closed Graph Theorems. V. PTAK — 1966 Mathematische Annalen
On Uniform Continuity of the Spectral Radius in Banach Algebras. V. Pták; J. Zemánek — 1977 Manuscripta mathematica
Some Generalizations of Positive Definiteness and Monotonicity. M. FIEDLER; V. PTÁK Numerische Mathematik
Banach algebras with involution Pták, V. — 1972 General Topology and its Relations to Modern Analysis and Algebra