The letter æ does not seem to be supported by pdflatex (TeXLive 2017)
A document with \cite{AlnaesLoggMardalSkavhaugLangtangen:2009:1}
does not correctly display æ while cite{Oksendal:2000:1}
correctly shows the letter Ø.
A document with \cite{AlnaesLoggMardalSkavhaugLangtangen:2009:1}
does not correctly display æ while cite{Oksendal:2000:1}
correctly shows the letter Ø.