Citation in Latex citation is undefined
I use latex with citavi for a few weeks now, and everything worked well.
Today I tried to add 2 new book-sources. The Sources are in the bibliography-file, but when I try to cite them, there only appears
and I get an error message "citation in line 15 is undefined".
All the other citations still work properly. Only the 2 new ones make thes problems.
Edit: I forgot to mention: The 2 new inserted also don't appear at the bibliography of my script
Has anyone an idea how this can be solved?