使用 natbib 和 imakeidx 进行作者索引

Question

我希望生成一个引用作者的索引。我在文档中使用imakeidx和natbib调用\citeindextrue，但引用似乎没有在生成的 .idx 文件中注册（手动输入的关键字确实被编入索引）。

下面是一个最小的例子，它输出仅包含两个条目（“key”和“word”）的参考书目和索引。

\documentclass{article}
\usepackage{natbib}
\usepackage{imakeidx}
\makeindex

\begin{filecontents}{anc.bib}
@Book{Frede1987,
  Title                    = {Essays in Ancient Philosophy},
  Author                   = {Michael Frede},
  Publisher                = {University of Minnesota Press},
  Year                     = {1987}
}
@InCollection{Frede1990,
  Title                    = {An Empiricist View of Knowledge: Memorism},
  Author                   = {Michael Frede},
  Booktitle                = {Companions to Ancient Thought 1: Epistemology},
  Publisher                = {Cambridge University Press},
  Year                     = {1990},
  Editor                   = {Stephen Everson},
  Pages                    = {225-250}
}
@Book{Lorenz2006,
  Title                    = {The Brute Within},
  Author                   = {Hendrik Lorenz},
  Publisher                = {Oxford University Press},
  Year                     = {2006}
}
\end{filecontents} 

\begin{document}

\citeindextrue

Some citations: \citet[243--60]{Frede1987} and \citet[227--34]{Frede1990} and also \citet[4--7]{Lorenz2006}. Some keywords: \index{key} key, \index{word} word.

\bibliographystyle{unsrtnat}
\bibliography{anc}
\printindex

\end{document}

我希望制作一个包含“关键词”、“词”以及每个引用作者的页码和作者姓名的索引。我试过了makeidx：结果相同。