An up-spectral space need not be A -spectral. Echi, Othman, Gargouri, Riyadh (2004) The New York Journal of Mathematics [electronic only]
Application on local discrete expansion. Abd El-Monsef, M.E., Kozae, A.M., Abo Khadra, A.A. (1996) International Journal of Mathematics and Mathematical Sciences
Are most measurable functions one-to-one? van Douwen, E.K., Stone, A.H. (1992) Portugaliae mathematica