\if@twoside
\def\ps@headings{%
\let\@oddfoot\@empty\let\@evenfoot\@empty
\def\@evenhead{\thepage\hfil\slshape\leftmark}%
\def\@oddhead{{\slshape\rightmark}\hfil\thepage}%
\let\@mkboth\markboth
\def\chaptermark##1{%
\markboth {\MakeUppercase{%
\ifnum \c@secnumdepth >\m@ne
\if@mainmatter
\@chapapp\ \thechapter. \ %
\fi
\fi
##1}}{}}%
\def\sectionmark##1{%
\markright {\MakeUppercase{%
\ifnum \c@secnumdepth >\z@
\thesection. \ %
\fi
##1}} }}
\else
\def\ps@headings{%
\let\@oddfoot\@empty
\def\@oddhead{{\slshape\rightmark}\hfil\thepage}%
\let\@mkboth\markboth
\def\chaptermark##1{%
\markright {\MakeUppercase{%
\ifnum \c@secnumdepth >\m@ne
\if@mainmatter
\@chapapp\ \thechapter. \ %
\fi
\fi
##1}} }}
\fi