2014-05-28 Twenty days after I've fixed the exported data of Zotero, [0] I investigated into the problem. This is possible because Zotero is Free Software! (AGPL 3) The export modules are collected in. [1] And there was the bib- tex export, [2] including the `\\'i', the ``latin small letter i with acute'', which caused the problems. But wait, there is also a biblatex exporter module. [3] And then I realized my problem: I had tried to feed the bibtex export to the biblatex engine. This was the moment when I realized that bibtex and biblatex are two different things ... well! Using Zotero's biblatex export didn't cause any problems. [0] http://marmaro.de/lue/txt/2014-05-08.txt [1] https://github.com/zotero/translators [2] https://github.com/zotero/translators/blob/master/BibTeX.js [3] https://github.com/zotero/translators/blob/master/BibLaTeX.js http://marmaro.de/lue/ markus schnalke