References
- Dugundji , J. 1966 . Topology , Boston : Allyn and Bacon .
- Hudson , J.F.P. 1969 . Piecewise Linear Topology , New York, NY : W.A. Benjamin .
- Kolyada , S. , Snoha , L. and Trofimchuk , S. 2001 . Noninvertible minimal maps . Fundam. Math. , 168 : 141 – 163 .