Biblatex: How to add comment to autocite?

Question

I am trying to add some text to a citation that is put as a footer. The citation references to an earlier citation but has a different page. So far it works like this:

While Adams himself does not think that his premise (4) 
is very debatable\autocite[347-348]{RobertAdams1991}, blabla

Now I want to add some text after the "348."

How can I accomplish this?

Answer 1

You have two options:

1. Using the same citation mecanism you're already working with, you can add any kind of information to the postnote argument: Just keep in mind that if the contents of this argument is not numerical, biblatex will not be able to automatically format it: biblatex can turn [347-348] into pp.~347-348 (or [347--348] into pp.~347--348), but it does not know what is a page range and what is a textual note in [347-348, see also his earlier work]. In other words, it can parse number ranges as page ranges, but anything else will disturb this automation and be treated as a textual string. So you should use \autocite[\ppno~347--348, see his earlier work]{RobertAdams1991} as suggested by moewe. See §3.7.1 (as well as §3.7.8, on \pno, \ppno and other commands related to page ranges notation) of the documentation.

2. An alternative would be to use the multicite mechanism:\autocites(see also his earlier work)[347-348]{RobertAdams1991}. Multicite commands allow a different notation for “global” pre and post-notes (i.e., notes printed before and after the whole citation command), via \autocites(<multiprenote>)(<multipostnote>)[<prenote 1>][<postnote 1>]{<entry 1>}[<prenote n>][<postnote n>]{<entry n>} Just like with regular citation commands, when there's only one of the arguments it treats it as the post-note. See § 3.7.3 of the documentation.

Here's a MWE exploring these possibilities:

\documentclass{article}
\usepackage[style=authoryear]{biblatex}
\addbibresource{biblatex-examples.bib}
\begin{document}
\thispagestyle{empty}

\autocite[347--348]{knuth:ct} is the same as
\autocite[\ppno~347--348]{knuth:ct}

\autocite[347--348, see also his earlier work]{knuth:ct} is
\emph{not} the same as \autocite[\ppno~347--348, see also his earlier
work]{knuth:ct}

Another option is to use the multicite mechanism: \autocites(see also
his earlier work)[347--348]{knuth:ct} (which is the same as
\autocites()(see also his earlier work)[][347--348]{knuth:ct} 

\end{document}