The bibtex (and other export options) are among the oldest parts of code of pybliometrics - when it was called scopus and maintained only by @jkitchin. Do you remember why just for journal articles? I think it's not restricted by the API, is it?

For all of these export options it'd be great to use another library and provides easy conversion between all the types. Currently everything is hard-coded.

Alright. I started working on a function that improves the current situation (but that is only for BibTeX export).

Maybe we can discuss that.

I think the restriction to Journal articles might just have been a decision to make implementation easy.

You're probably right!

A PR to address this issue will be most welcome!

Alright. I'll continue to work on it for my own usage and hopefully can contribute with a PR, soon. Some help with internals is very welcomed!

Just some update: The issue is not forgotten. As per our call, I also use an external library for the bibtex handling now, which might help a little with performance and possibly robustness (although also introduced quite some problems to tackle). Currently, I based it on the ScopusSearch class (as opposed to the AbstractRetrieval class before) for better performance.