## BibTeX

> [BibTeX](https://www.ctan.org/pkg/bibtex) is a file format and reference management system commonly used in conjunction with `LaTeX` typesetting. It serves as a way to organize and store bibliographic information for academic and research documents.

`BibTeX` files have a `.bib` extension and consist of plain text entries representing references to various publications, such as books, articles, conference papers, theses, and more. Each `BibTeX` entry follows a specific structure and contains fields for different bibliographic details like author names, publication title, journal or book title, year of publication, page numbers, and more.

BibTeX files can also store the path to documents, such as `.pdf` files that can be retrieved.

## Installation[​](#installation "Direct link to Installation")

First, you need to install `bibtexparser` and `PyMuPDF`.

```
%pip install --upgrade --quiet  bibtexparser pymupdf
```

## Examples[​](#examples "Direct link to Examples")

`BibtexLoader` has these arguments: - `file_path`: the path of the `.bib` bibtex file - optional `max_docs`: default=None, i.e. not limit. Use it to limit number of retrieved documents. - optional `max_content_chars`: default=4000. Use it to limit the number of characters in a single document. - optional `load_extra_meta`: default=False. By default only the most important fields from the bibtex entries: `Published` (publication year), `Title`, `Authors`, `Summary`, `Journal`, `Keywords`, and `URL`. If True, it will also try to load return `entry_id`, `note`, `doi`, and `links` fields. - optional `file_pattern`: default=`r'[^:]+\.pdf'`. Regex pattern to find files in the `file` entry. Default pattern supports `Zotero` flavour bibtex style and bare file path.

```
from langchain_community.document_loaders import BibtexLoader
```

```
# Create a dummy bibtex file and download a pdf.import urllib.requesturllib.request.urlretrieve(    "https://www.fourmilab.ch/etexts/einstein/specrel/specrel.pdf", "einstein1905.pdf")bibtex_text = """    @article{einstein1915,        title={Die Feldgleichungen der Gravitation},        abstract={Die Grundgleichungen der Gravitation, die ich hier entwickeln werde, wurden von mir in einer Abhandlung: ,,Die formale Grundlage der allgemeinen Relativit{\"a}tstheorie`` in den Sitzungsberichten der Preu{\ss}ischen Akademie der Wissenschaften 1915 ver{\"o}ffentlicht.},        author={Einstein, Albert},        journal={Sitzungsberichte der K{\"o}niglich Preu{\ss}ischen Akademie der Wissenschaften},        volume={1915},        number={1},        pages={844--847},        year={1915},        doi={10.1002/andp.19163540702},        link={https://onlinelibrary.wiley.com/doi/abs/10.1002/andp.19163540702},        file={einstein1905.pdf}    }    """# save bibtex_text to biblio.bib filewith open("./biblio.bib", "w") as file:    file.write(bibtex_text)
```

```
docs = BibtexLoader("./biblio.bib").load()
```

```
{'id': 'einstein1915', 'published_year': '1915', 'title': 'Die Feldgleichungen der Gravitation', 'publication': 'Sitzungsberichte der K{"o}niglich Preu{\\ss}ischen Akademie der Wissenschaften', 'authors': 'Einstein, Albert', 'abstract': 'Die Grundgleichungen der Gravitation, die ich hier entwickeln werde, wurden von mir in einer Abhandlung: ,,Die formale Grundlage der allgemeinen Relativit{"a}tstheorie`` in den Sitzungsberichten der Preu{\\ss}ischen Akademie der Wissenschaften 1915 ver{"o}ffentlicht.', 'url': 'https://doi.org/10.1002/andp.19163540702'}
```

```
print(docs[0].page_content[:400])  # all pages of the pdf content
```

```
ON THE ELECTRODYNAMICS OF MOVINGBODIESBy A. EINSTEINJune 30, 1905It is known that Maxwell’s electrodynamics—as usually understood at thepresent time—when applied to moving bodies, leads to asymmetries which donot appear to be inherent in the phenomena. Take, for example, the recipro-cal electrodynamic action of a magnet and a conductor. The observable phe-nomenon here depends only on the r
```