Manage Literature with Emacs BibTeX Mode

Emacs ships with bibtex-mode, a major mode to create and manage bibliographies. This mode, as the name suggests, uses the BibTeX file format as your default literature database. BibTeX is a plain text format to manage literature and citations and is typically used for LaTeX typesetting, but also perfectly integrates with Org mode. A typical entry for a book will look like this:

@article{stallman_1981_emac,
  title      = {{{EMACS}} the Extensible, Customizable Self-Documenting Display Editor},
  author     = {Stallman, Richard M.},
  year       = 1981,
  journal    = {ACM SIGOA Newsletter},
  volume     = 2,
  number     = {1-2},
  pages      = {147--156},
  doi        = {10.1145/1159890.806466},
  keywords   = {Emacs}
  file       = {computing/stallman-1981-emacs.pdf}
}

Each entry starts with an @-sign and the entry type, followed by a curly brace and a unique citation key. The following lines contain the relevant data about this entry, in this example, the earliest publication about Emacs.

BibTeX can process different types of literature, such as articles and conference papers, each of which has its own field types. BibTeX ignores any field names that are not recognised, which provides opportunities to use the file for other purposes, such as attaching files and keywords.

BibTeX is a plain text file with the .bib extension. You can store one or more bibliography files in a central folder to refer to them from anywhere in Emacs. You can also attach specific BibTeX files to an Org mode file to set a bibliography for a project.

You don’t need to install any packages to get started. Just created an empty file with a .bib extension, and Emacs enables bibtex-mode when you open the file.

Emacs bibtex-mode uses templates to add new entries. To add a reference, use the bibtex-entry function (C-c C-b). Use the minibuffer completion to select the relevant type. Emacs also provides a shortcut for every kind of literature, which you can see with C-c C-e C-h.

Each entry type has at least one compulsory field. Any optional fields start with OPT. For fields that begin with ALT, such as author or editor, you must complete at least one of them.

Jump from field to field with C-j (bibtex-next-field) and complete all required fields and one of the ALT fields. When you’re done, press C-c twice (bibtex-clean-entry) to check the syntax and remove empty fields. This function also assigns a citation key to the entry using some configurable rules, but you can also set one manually.

To enter names, place the family name first, followed by a comma and the first name or initials. Any additional authors are separated by “and”, e.g. "Hawking, S. and Penrose, R.".

If you copy and paste an author name, or it is automatically inserted using the biblio tool discussed below, the first and family name might be the wrong way around. A nice Emacs hack is to use the org-transpose-words function, bound to M-t. This function swaps the order of two words, for example from "Richard Stallman" to "Stallman Richard".

To align the lines of each entry, you can also use the bibtex-fill-entry function (C-c C-q). The table below summarises the most salient keyboard shortcuts and functions in bibtex-mode.

  ;; Managing Bibliographies
  (use-package bibtex
    :custom
    (bibtex-dialect 'BibTeX)
    (bibtex-user-optional-fields
     '(("keywords" "Keywords to describe the entry" "")
       ("file" "Link to a document file." "" )))
    (bibtex-align-at-equal-sign t))

  (bibtex-set-dialect 'biblatex)

  ;; Biblio package for adding BibTeX records and download publications
  (use-package biblio)

Several Emacs packages are available that link bibliography files to notes. The Ebib, Helm-BibTeX and Ivy-BibTeX each use their own completion system. The Citar package uses the standard minibuffer completion mechanism to access your bibliographies. This package provides access to hyperlinks, notes, attachments and the source bibliography file. Citar also integrates with org-cite, Org mode’s citation module.

Within the Org mode system, you can have two types of bibliographies. The global bibliography is a set of BibTeX files available from anywhere within Emacs. You can also link one or more project-specific local BibTeX files to an Org mode file, discussed in the article about bibliographic notes.

The ews-bibtex-directory variable stores the location of all BibTeX files and their associated attachments. This variable is defined in the article on Emacs configuration. By default, this variable is set at ~/Documents/library/.

You store all your BibTeX files and the associated attachments in this location. BibTeX files have to reside in this directory, attachments can be in subdirectories. Any file paths for BibTeX entries start at this path. For example, when the BibTeX entry states: file = {computing/stallman-1981-emacs.pdf}, the attachment is stored at: ~/Documents/library/computing/stallman-1981-emacs.pdf

The EWS configuration creates a new variable named ews-bibtex-file which lists the .bib files in the ews-bibtex-directory that start with a letter or a number (to exclude backup and hidden files). This code is a regular expression, which is a powerful method to find text. If you add another bibliography file, you will have to rerun the configuration code, or restart Emacs to register it.

If you add or remove any bibliography files from the bibliography directory, then use the ews-bibtex-register function to register the new set of bibliographies. You don't need to do this when you add new entries to a file, only when adding, renaming or removing a file.

Citations are further discussed in another article.

  ;; Citar to access bibliographies
  (use-package citar
  :defer t
  :custom
  (citar-bibliography ews-bibtex-files)
  :bind
  (("C-c w b o" . citar-open)))

Open the Citar menu with citar-open (C-c w b o) and select the literature you seek.

Finding literature with Citar is easy. After every keystroke in the Citar menu, the list of options is narrowed to the relevant matches. Select your candidate with the arrow keys and hit Enter. Use the Tab key to select more than one entry.

The first three columns in the menu indicate which entries include a hyperlink (L), one or more attached files (F) and an associated note (N). The configuration for taking bibliographic notes is explained in another article. You can filter the Citar completion menu for entries with notes using :n, showing only entries with an attachment use ":f" and entries that have links with ":l".

After hitting Enter, Citar provides a popup menu in the minibuffer from where you can open any attachments, create a new note or open an existing note and follow any hyperlinks listed in the BibTeX entry.

The Biblio package is useful, but one minor inconvenience is that you must jump to the relevant bibliography file before inserting a new entry. It also provides two separate search functions.

The bespoke ews-bliblio-lookup (C-c w b b) function lets you select the BibTeX file where you would like to store the search results before choosing one of the available sources. This function also combines searching for DOIs with the other sources, removing some steps from your workflow.

If you like to support my work, then please purchase the Emacs Writing Studio book.

You can find the source files for the book and the latest configuration files on GitHub:

emacs-writing-studio

Emacs is a malleable system, so everybody will have their personal preferences to undertake a task. Any article on how to use Emacs is thus opinionated. If you have a different way of doing things, please complete the contact form to send me an email or contact me on social media.

The next article explains how to create bibliographic notes with the Citar-Denote package.