Overleaf / Latex: reference several bib files in parallel and "merge" them into a common literature directory

Question

Overleaf / Latex:

How can I reference several parallel *.bib files in one single Latex project and create a common literature directory at the end without having to merge these two files?

Thanks a lot for your help!

I have already seen approaches that create several (mostly 1:1) bibliographies from several bib files using different packages (for example), but I have not yet found an approach or solution to my question above. If there is already a suitable entry, then I simply haven't found it and apologise for this... I hope I have defined the requirements clearly enough. If there is any missing information, please ask again and I will add it immediately.

Answer 1

If you are ok to use biblatex, you don't have to merge your libraries. Just add as many files as you need via multiple instances of \addbibresournce{<folder>/<file>}. Repeat the command for all required files that contain your references. This will work as long as <folder name> exists and is in the current project folder.

Consider the code below. Let's say all files are gathered in the bib/, which is in the current project folder. Run the example below and all references should appear in the PDF, all loaded from separate files. Make sure bin/ folder exists.

Notice the blocks of \begin{filecontents*}...\end{filecontents}`, which are only required to make the example self-contained as they create the file during compilation. In real case, the files would already exist.

The code

%%% --- THIS BLOCK CREATES files ---
\begin{filecontents*}[overwrite]{bib/sample1.bib}
@article{ref:einstein,
    author = "Albert Einstein",
    title = "{Zur Elektrodynamik bewegter K{\"o}rper}. ({German})
    [{On} the electrodynamics of moving bodies]",
    journal = "Annalen der Physik",
    volume = "322",
    number = "10",
    pages = "891--921",
    year = "1905",
    DOI = "http://dx.doi.org/10.1002/andp.19053221004",
    keywords = "physics"
}
\end{filecontents*}
\begin{filecontents*}[overwrite]{bib/sample2.bib}
@book{ref:dirac,
    title = {The Principles of Quantum Mechanics},
    author = {Paul Adrien Maurice Dirac},
    isbn = {9780198520115},
    series = {International series of monographs on physics},
    year = {1981},
    publisher = {Clarendon Press},
    keywords = {physics}
}
\end{filecontents*}
\begin{filecontents*}[overwrite]{bib/sample3.bib}
@online{ref:knuthwebsite,
    author = "Donald Knuth",
    title = "Knuth: Computers and Typesetting",
    url  = "http://www-cs-faculty.stanford.edu/~uno/abcde.html",
    addendum = "(accessed on 20/09/2023)",
    keywords = "latex,knuth"
}
\end{filecontents*}
\begin{filecontents*}[overwrite]{bib/sample4.bib}
@inbook{ref:knuth-fa,
    author = "Donald E. Knuth",
    title = "Fundamental Algorithms",
    publisher = "Addison-Wesley",
    year = "1973",
    chapter = "1.2",
    keywords  = "knuth,programming"
}
\end{filecontents*}
%%% --- END --- %%%

%%% REGULAR LATEX DOCUMENT STARTS HERE 
\documentclass{article}
\usepackage[
  backend=biber,
  style=apa,
  url=false,
]{biblatex}
\usepackage[colorlinks]{hyperref}
\usepackage[nopar]{kantlipsum}

\addbibresource{bib/sample1.bib}
\addbibresource{bib/sample2.bib}
\addbibresource{bib/sample3.bib}
\addbibresource{bib/sample4.bib}


\begin{document}
\section{Introduction}\label{sec:intro}
\kant[1][1] \autocite{ref:einstein}.

\section{Main section}\label{sec:main}
\kant[1][2] \autocite{ref:dirac}.

\section{Simple implementation}\label{sec:implementation}
\kant[1][3] \autocite{ref:knuthwebsite}.

\section{Conclusion}\label{sec:conclusion}
\kant[1][4] \autocite{ref:knuth-fa}.

\printbibliography
\end{document}