How to cite part of online entry (website chapter) in BibLaTex?

Question

I want to cite a part of a web page. Something analogical to a chapter of a book. But from the documentation, the @online entry only has subtitle and titleaddon fields which seem somehow relevant, but from my understanding serve to display a title referencing the whole article, not part of it.

(The website I want to reference.) What I'm currently doing is:

@online{parallel-computing,
    author = "Blaise Barney",
    title = "Introduction to Parallel Computing",
    url = "https://computing.llnl.gov/tutorials/parallel_comp/#Whatis"
}

And I'd like to specifically refer to the part What is Parallel Computing?, which I'm currently referencing with the URL (don't know if that's appropriate).

Answer 1

For this particular example (and I guess for most website with their own URL) I would just use @online to refer to the complete website and give the 'section' in the postnote of the citation to refer to the specific part. Much like one normally adds the complete @book to the bibliography, but only cites a specific page.

\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage[style=authoryear, backend=biber]{biblatex}


\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@online{parallel-computing,
  author       = {Blaise Barney},
  title        = {Introduction to Parallel Computing},
  url          = {https://computing.llnl.gov/tutorials/parallel_comp},
  urldate      = {2019-08-06},
  organization = {Lawrence Livermore National Laboratory},
}
\end{filecontents}

\addbibresource{\jobname.bib}
\addbibresource{biblatex-examples.bib}


\begin{document}
Lorem ipsum \autocite[section \enquote{What is Parallel Computing?}]{parallel-computing}.
\printbibliography
\end{document}

To me the most natural, self-contained unit in this case just appears to be the complete website.

---

If you insist that the specific section be referenced in the bibliography, you can follow David Purton's advice from the comments and (ab)use the @inbook entry type.

\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage[style=authoryear, backend=biber]{biblatex}


\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@inbook{barney:whatis,
  author       = {Blaise Barney},
  booktitle    = {Introduction to Parallel Computing},
  title        = {What is Parallel Computing?},
  url          = {https://computing.llnl.gov/tutorials/parallel_comp/#Whatis},
  urldate      = {2019-08-06},
  publisher    = {Lawrence Livermore National Laboratory},
}
\end{filecontents}

\addbibresource{\jobname.bib}
\addbibresource{biblatex-examples.bib}


\begin{document}
Lorem ipsum \autocite{barney:whatis}.
\printbibliography
\end{document}

---

Of course it would be possible to define a new entry type called @inonline that relates to @online as @inbook relates to @book. At the moment I doubt this is worth the effort, but it is most certainly doable. See How can I create entirely new data types with BibLaTeX/Biber? for a starter.

Alternatively, Bib Formatting Question shows how you could add maintitle to @online entries so that you could have something like

@online{barney:whatis,
  author       = {Blaise Barney},
  maintitle    = {Introduction to Parallel Computing},
  title        = {What is Parallel Computing?},
  url          = {https://computing.llnl.gov/tutorials/parallel_comp/#Whatis},
  urldate      = {2019-08-06},
  organization = {Lawrence Livermore National Laboratory},
}