\catcode `\@=11\relax 
\Z { Introduction}{1}{1}
\Z { Strategic considerations}{8}{4}
\Z { Basic input routines}{9}{5}
\Z { Dictionary lookup}{17}{9}
\Z { The frequency counts}{32}{15}
\Z { Sorting a trie}{36}{16}
\Z { The endgame}{41}{18}
\Z { Index}{42}{19}

\catcode `\@=12\relax