\documentclass{langscibook}
\author{Pat Jaeung}
\title{Sample monograph}
\subtitle{}

\renewcommand{\lsSeries}{cfls}
\renewcommand{\lsSeriesNumber}{123}
\renewcommand{\lsISBNdigital}{000-0-000000-00-0}
\renewcommand{\lsISBNhardcover}{000-0-000000-00-0}
\renewcommand{\lsISBNsoftcover}{000-0-000000-00-0}
\renewcommand{\lsID}{000}
% \BookDOI{}%ask coordinator for DOI

\dedication{For Mom and Dad}
\typesetter{Jane Doe}
\proofreader{John Doe}
\BackBody{What everyone should know about monographs: it's here}

\bibliography{langsci-test}
\begin{document}
\maketitle
\frontmatter
\currentpdfbookmark{Contents}{name} % adds a PDF bookmark
\tableofcontents
\mainmatter
\chapter{Introduction}
This is the introduction.
\chapter{New research}
This is the main argument \citep{Chomsky1957}.
\chapter{Conclusion}
This is the conclusion.

\backmatter
\sloppy
\phantomsection%this allows hyperlink in ToC to work
\printbibliography[heading=references]
\cleardoublepage

\phantomsection
\addcontentsline{toc}{chapter}{Index}
\addcontentsline{toc}{section}{\lsNameIndexTitle}
\ohead{\lsNameIndexTitle}
\printindex
\cleardoublepage

\phantomsection
\addcontentsline{toc}{section}{\lsLanguageIndexTitle}
\ohead{\lsLanguageIndexTitle}
\printindex[lan]
\cleardoublepage

\phantomsection
\addcontentsline{toc}{section}{\lsSubjectIndexTitle}
\ohead{\lsSubjectIndexTitle}
\printindex[sbj]
\ohead{}

\end{document}