@inbook{TBB,
title = {Extrema (Appendix on extremal problems for realvalued functions of two variables)},
author = {Jozef Doboš},
url = {http://classicalrealanalysis.info/documents/PagesfromTBB-Appendix-Extrema-June7-20081.pdf},
year = {2008},
date = {2008-02-01},
booktitle = {CLASSICALREALANALYSIS.INFO},
keywords = {real functions}
}