# Multiple bibliographies, multiple styles, discontiguous regions

What I currently have:

• My master's thesis (modified book class) which consists of the following:

• Chapter 1: a single file.
• Chapter 2: five files, one section per file.
• Chapter 3: a single file.
• A single bibliography for all three chapters in APA format.

What I now need:

• I need chapter two to have its own bibliography in a format which is not APA.
• I need chapters one and three to have their own bibliography in APA format.

I read the biblatex documentation on multiple bibliographies and I'm not sure how to pull this off. The section argument to \printbibliography only takes a single value, so I'm not sure how to merge the two chapters. And I have no idea how to use two different formats in the same document.

While it is no problem to produce separate bibliographies for each chapter using refsections or refsegments, there are two major obstacles for your needs.

To understand the first one recall that refsections are kept completely separate and independent from each other. That means that you can cite the same work in two refsections and it might get a different label in each (think numeric labels or the extradate disambiguation letter). refsections are implemented in a way that makes it impossible to 'merge' two sections, you have already seen one symptom of this: the section argument only accepts one number. refsegments on the other hand have no separation and independence of data, they basically only add an internal keyword to each entry that can be used for filtering by place of appearance later.

Your first problem is to find a sensible setup in terms of refsections and refsegments.

• Option 1 would be to use refsegments for all chapters. It is then very easy to filter the \printbibliography by segment and even by multiple segments.

In this option all entries will still be treated together for the purposes of sorting and disambiguation. This may or may not be desired (I think in this case it would not be desired).

The fact that all entries basically live in the same environment makes it even more complicated to mix-and-match two styles than it already is (see below).

• Option 2 uses the fact that while it is not possible to merge refsections or have real split refsections, refsection 0 is special. All entries that are not within an explicit refsection belong to refsection 0, so 0 is the only 'splitable' refsection.

Hence something like

\begin{document}
\chapter{Chapter One}               % default refsection 0
Lorem\cite{sigfridsson,worman}

\begin{refsection}                  % refsection 1
\chapter{Chapter Two}
Ipsum\cite{knuth:ct:a,sigfridsson}
\printbibliography
\end{refsection}                    % go back to 0

\chapter{Chapter Three}
Dolor\cite{sigfridsson,nussbaum}
\end{document}


might work. It does not scale since only refsection 0 is allowed to be split, but that might just be enough for you.

A refsection approach would mean that the bibliography of chapter 1 is independent of that of the chapters 1 and 3.

Your second problem is that of having two different citations and bibliography styles in one document.

Officially there is no way to have different bibliography and citation styles (the basic situation in this regard has not really changed since biblatex: multiple styles). Depending on the specifics of each case it is sometimes possible to rustle up a short solution (see for example Two bibliographies with two different styles in the same document, Biblatex: Two bibliographies with different styles and sortings, biblatex: different bibstyles in the same document?), but I'm having my doubts in this case. APA style is quite complicated and if your desired non-APA style is very different that could pose quite a problem.

• That all said, while I can sometimes see the appeal in different bibliography and citations styles and split bibliographies, in this case the requirements seem to be a bit too arbitrary. Changing the citation style for a chapter just seems odd. And I still don't quite understand where the bibliography for chapter 1 and 3 should go? Is it one bibliography at the end? – moewe Aug 17 '18 at 6:09
• refsection 0 is the perfect solution for merging Chapters 1 and 3. I think that will actually work! With regard to the apparently-arbitrary requirements, they are due to the fact that my department requires APA citation/reference style for its theses except when chapters are to be published as papers in other journals in which case those chapters are to use whatever style that journal uses and my PI had the unfortunate luck in choosing a journal which prefers a style which is distinctly different from APA. – Jack Twilley Aug 17 '18 at 15:49
• Also, the bibliography for Chapter 2 will be within that chapter while the bibliography for Chapters 1 and 3 will be after Chapter 3. – Jack Twilley Aug 17 '18 at 15:51
• @JackTwilley Ah, that is a very weird requirement and would certainly confuse me to no end if I were to read the thesis. Anyway for the split thingy refsection 0 does indeed seem to be a good match - the code snippet should do pretty much what you want if you add a \printbibliography at the end. Re the citation style: Since you keep things independent with refsections, you do have a chance of getting a different style, but you will have to resort to hacks. I guess you would have to ask a new question with more details for more specific help with that. – moewe Aug 17 '18 at 15:56
• I have accepted this answer because I have validated that it correctly addressed the multiple bibliographies with disjoint regions portion of the question. As for the style, I think you are correct in that I will have to ask that as its own question. – Jack Twilley Aug 21 '18 at 20:28