# Sorting sections by keyword unrecognized by biblatex

I am trying to divide my bibliography into two sections based on primary and secondary sources. I succeded at this once but since then my files have refused to distinguish entries by keywords. For instance, my MWE:

\documentclass[12pt, letterpaper]{article}

\usepackage[notes, backend=biber, cmsdate=both, longcrossref=true, delayvolume]{biblatex-chicago}
\bibliography{Bibliography}

\begin{document}

\nocite{*}
words etc.  \par

\begin{center}
{\normalsize{\textbf{Bibliography}}} %title
\end{center}
\printbibliography[keyword=primary,title={Primary Sources}]
\printbibliography[keyword=secondary,title={Secondary Secondary}]

\end{document}


And the examples sources from the Bibliography.bib file:

@book{williamcobbett,
title={William Cobbett},
author={Chesterton, G.K.},
year={[1920]},
location = {London},
keywords = {primary},
publisher={Hodder \& Stoughton}
}

@book{doweagree,
title={Do We Agree?},
subtitle = {A Debate Between G.K. Chesterton and Bernard Shaw with Hilaire Belloc in the Chair},
year={1928},
location = {Hartford, CT},
keywords = {primary},
publisher={Edwin Valentine Mitchell}
}

@book{buildingjerusalem,
title={Building Jerusalem},
subtitle = {The Rise and Fall of the Victorian City},
author={Hunt, Tristram},
year={2004},
location = {London},
keywords = {secondary},
publisher={Weidenfeld \& Nicolson}
}

@book{salvationarmy,
author = {Walker, Pamela J.},
title= {Pulling the Devil's Kingdom Down: The Salvation Army in Victorian Britain},
location = {Berkeley, CA},
publisher = {University of California Press},
year = {2001},
keywords = {secondary}
}


When I compile this it does print the bibliography, but only once and with all four sources, like it would if I hadn't told it to sort keywords. How can I get it to recognize the division?

• This prints two bibliographies with two entries each, but because you completely removed the title with \defbibheading{bibliography}[\refname]{} you can barely see a difference between the two bibliographies. Remove the \defbibheading{bibliography}[\refname]{} and try again. – moewe Mar 17 '18 at 17:43
• Great, that worked. I knew I had to be missing something simple. – Richard Mar 17 '18 at 17:53

You are actually getting two bibliographies here. The space between the second and the third entry is just slightly larger than it would be if the two entries were actually produced by the same \printbibliography. You could also see that you have two bibliographies here if you look at the sorting, but in the example at hand the sorting of the two bibliographies we have here is the same that we would get if there was only one bibliography.
With \defbibheading{bibliography}[\refname]{} you have completely removed the title of the bibliography. If you remove that line you'll clearly see that you actually have two bibliographies, each with its own heading.
\printbibheading[title=\bibname]