de Groot, J.: On the topological characterization of manifolds.
(English).
In:
Novák, J. (ed.): General Topology and its Relations to Modern Analysis and Algebra.
Proceedings of the Third Prague Topological Symposium, 1971.
Academia Publishing House of the Czechoslovak Academy of Sciences, Praha, 1972.
pp. 155-158
Tikhomirov, V. M.; Tumarkin, L. A.: О поперечниках Урысона $n$-мерной Эвклидовой сферы.
(Russian) [The Uryson diameters of the Euclidean $n$-sphere].
In:
Novák, J. (ed.): General Topology and its Relations to Modern Analysis and Algebra.
Proceedings of the Third Prague Topological Symposium, 1971.
Academia Publishing House of the Czechoslovak Academy of Sciences, Praha, 1972.
pp. 441-442