Separate references for appendix, without duplicates with main body (automatically handled)

Question

I would like to automatically put in one section all the references that are coming from the main text, and in another section all the references that are coming from the Appendix and which are not already cited in main text.

I'm aware of this question, but it does not solve my issue since:

• either duplicated references are not removed from the appendix
• either I have to manually tag each reference (by using a different cite command or a different .bib file), and I don't want to do that myself as it's super hard to always keep track of where citations appear in a constantly moving text with potentially multiple co-authors.

I'm fine with either bibtex or biblatex solutions.

MWE:

\documentclass{article}

\usepackage{filecontents}
\usepackage{biblatex}

\begin{filecontents}{myrefs.bib}
@Book{Knuth:1990,
    author    = {Knuth, Donald E.},
    title     = {The {\TeX}book},
    year      = {1990},
    isbn      = {0-201-13447-0},
    publisher = {Addison\,\textendash\,Wesley},
}

@Book{Lamport:94,
    author    = {Lamport, Leslie},
    title     = {\LaTeX: A Document Preparation System},
    year      = {1994},
    isbn      = {0-021-52983-1},
    publisher = {Addison\,\textendash\,Wesley},
}
\end{filecontents}

\addbibresource{myrefs.bib}
\begin{document}

\section{First}
    {\LaTeX} is aTuring-complete
    (procedural) markup language and
    typesetting processor~\parencite{Lamport:94}.


\printbibliography
\appendix
\section{Second}
\begin{refsection}
   The ultimate reference of {\TeX} is~\parencite{Knuth:1990} and \parencite{Lamport:94}, which should NOT be cited in this section.
   \printbibliography[heading=subbibliography]
\end{refsection}

\end{document}

Answer 1

I found a solution for biblatex, which combines filters and refsegment.

\documentclass{article}

\usepackage{filecontents}
\usepackage[style=trad-alpha]{biblatex}

\begin{filecontents}{myrefs.bib}
@Book{Knuth:1990,
    author    = {Knuth, Donald E.},
    title     = {The {\TeX}book},
    year      = {1990},
    isbn      = {0-201-13447-0},
    publisher = {Addison\,\textendash\,Wesley},
}

@Book{Lamport:94,
    author    = {Lamport, Leslie},
    title     = {\LaTeX: A Document Preparation System},
    year      = {1994},
    isbn      = {0-021-52983-1},
    publisher = {Addison\,\textendash\,Wesley},
}
\end{filecontents}

\addbibresource{myrefs.bib}
\defbibfilter{appendixOnlyFilter}{
  segment=1 % Segment 1 will be chosen to be the one in appendix
  and not segment=0 % Default segment is 0
}

\begin{document}

\section{Main Body}
{\LaTeX} is aTuring-complete (procedural) markup language and typesetting processor~\cite{Lamport:94}.

\printbibliography[segment=0]
\appendix
\newrefsegment %% <== increases the segment number (0 by default)

\section{Appendix}
The ultimate reference of {\TeX} is~\cite{Knuth:1990} and \cite{Lamport:94}, which should NOT be cited in this section.
\printbibliography[heading=subbibliography,filter=appendixOnlyFilter]

\end{document}

Answer 2

You can use this template and create your own file within 3 minutes, which is very simple to use and will save you time and effort.

https://www.overleaf.com/latex/examples/multiple-bibliographies-with-bibunits/ktgbztpwjnpb

main.tex

\documentclass{article}
\usepackage[utf8]{inputenc}
\title{Multiple bibliographies with bibunits}

\usepackage{bibunits}

\begin{document}

\begin{bibunit}[plain]
\section{A section}
This is the first part with citations from \texttt{refs1.bib}, using the \texttt{plain} style. \cite{lees2010theoretical}

\putbib[refs1]
\end{bibunit}


\begin{bibunit}[alpha]
\section{Another section}
This is the first part with citations from \texttt{refs2.bib}, using the \texttt{alpha} style. \cite{belkin2002using,berard1994embedding}

\putbib[refs2]
\end{bibunit}


\end{document}

refs1.bib

@article{lees2010theoretical,
  title={Theoretical maximum capacity as benchmark for empty vehicle redistribution in personal rapid transit},
  author={Lees-Miller, John and Hammersley, John and Wilson, R},
  journal={Transportation Research Record: Journal of the Transportation Research Board},
  number={2146},
  pages={76--83},
  year={2010},
  publisher={Transportation Research Board of the National Academies}
}

refs2.bib

@inproceedings{belkin2002using,
  title={Using manifold stucture for partially labeled classification},
  author={Belkin, Mikhail and Niyogi, Partha},
  booktitle={Advances in neural information processing systems},
  pages={929--936},
  year={2002}
}

@article{berard1994embedding,
  title={Embedding Riemannian manifolds by their heat kernel},
  author={B{\'e}rard, Pierre and Besson, G{\'e}rard and Gallot, Sylvain},
  journal={Geometric \& Functional Analysis GAFA},
  volume={4},
  number={4},
  pages={373--398},
  year={1994},
  publisher={Springer}
}

ps: I searched Google for 2 hours. I even tried Overleaf's official solution: https://www.overleaf.com/learn/latex/Questions/Creating_multiple_bibliographies_in_the_same_document. It did not work. Then I found this link created by an Overleaf user.