Sorgenfrey, R. H. (1947). “On the topological product of paracompact spaces”. 《Bulletin of the American Mathematical Society》 (영어) 53: 631–632. doi:10.1090/S0002-9904-1947-08858-3. ISSN0273-0979.
Sorgenfrey, R. H. (1947). “On the topological product of paracompact spaces”. 《Bulletin of the American Mathematical Society》 (영어) 53: 631–632. doi:10.1090/S0002-9904-1947-08858-3. ISSN0273-0979.