In natbib
the References section is formatted using the macro \bibsection
, which is subsequently used by multibib
if used together with natbib
. The macro is defined as follows:
\section *{\refname \@mkboth {\MakeUppercase {\refname }}{\MakeUppercase {\refname }}}
This definition starts with \section
, which you can change into \subsection
(or anything else). Apart from modifying the source code, you can also 'patch' the command temporarily with \patchcmd
from the etoolbox
package. This macro takes five arguments: the command to patch, a search string, a replacement string, and two arguments which are executed in case the patching succeeds or fails, respectively, which can also be left empty. After you patch for the intermediate bibliography you can patch it back for the main bibliography.
MWE:
\documentclass[11pt]{article}
\begin{filecontents}{\jobname.bib}
@book{chicken:2010fj,
author = {Chicken, C},
title = {Chicken},
publisher = {Chicken Press},
year = {2010}
}
@book{turkey:2010jk,
author = {Turkey, T},
title = {Turkey},
publisher = {Turkey Press},
year = {2010}
}
\end{filecontents}
\usepackage{natbib}
\usepackage{multibib}
\usepackage{etoolbox}
\newcites{q}{Intermediate References}
\show\bibsection
\begin{document}
\section{On Chickens And Turkeys}
Regular reference: \citep{chicken:2010fj}. Intermediate reference: \citepq{turkey:2010jk}.
\bibliographystyleq{apalike}
\patchcmd{\bibsection}{\section}{\subsection}{}{}
\bibliographyq{\jobname.bib}
\bibliographystyle{apalike}
\patchcmd{\bibsection}{\subsection}{\section}{}{}
\bibliography{\jobname.bib}
\end{document}
Result:

Note that is also possible to print multiple bibliographies with biblatex
, see for example biblatex: Single out specific bibliography entries.