I am pretty sure you cannot use entry types that are not defined in bibtex-BibTeX-entry-alist or bibtex-biblatex-entry-alist. You can add types to those variables to get them to work.

John

-----------------------------------
Professor John Kitchin 
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803

On Sun, Sep 10, 2017 at 2:50 PM, Johannes Brauer <brauer@nordakademie.de> wrote:
Hi!

isn’t it allowed to use bibtex entries @url or @webpage? Using one of them the html export complains that the entry is not found, for example:

Carro1998 not found in /Users/johannes/Documents/lehre/Informatik/Programmierparadigmen/Vorlesung/referenzen.bib
org-ref-get-bibtex-entry-citation: Wrong type argument: stringp, nil

Johannes