"originally proved" ?
The article gives the impression that Tong proved the theorem first, and Katětov later improved it. However, the original papers seem to be
- Miroslav Katětov, On real-valued functions in topological spaces, Fundamenta Mathematicae 38 (1951), 85–91, 
- Hing Tong, Some characterizations of normal and perfectly normal spaces, Duke Mathematical Journal 19 (1952), 289–292, doi:10.1215/S0012-7094-52-01928-5
which implies the opposite order. How come? -- EJ (talk) 13:59, 12 March 2008 (UTC)
- I've changed the lead now. -- EJ (talk) 14:15, 18 March 2008 (UTC)