3.3. Formatting bibliography entries

The way references are formatted in the `{References}` or `{Bibliography}` environments must be different, depending on whether the citations use the [Author, Year] format, or whether they are bracketed numbers such as [39].

These paragraph shape changes are achieved by using the generic `{list}` environment. The diagram on page 76 of Kopka illustrates the relevant lengths `\labelwidth`, `\labelsep`, `\leftmargin`, and `\itemindent`. For either author-year or numeric citation style, the `\labelsep` length is set to one pica to separate the reference key from the body of the reference.

Because author-year citations may be lengthy, they are run-in to the reference entry, like this:

For the style shown above, the `\leftmargin` is set to a comfortable value (2 picas). The `\labelwidth` is set to zero, and the `\itemindent` set to minus the `\leftmargin` value, so the author's name starts flush left, with a hanging indentation on continuation lines.

If the references are cited by number, the entry is shaped like this:

Here, the `\labelwidth` is set according to the given sample text (e.g., “99”), plus square brackets. The `\leftmargin` is set to the sum of `\labelsep` and `\labelwidth`. The `\itemindent` is set to zero.