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I have a similar, may be very easy to find question:
I use bibunit for references at the end of each section.
All fine, but in the text the references with their numbers given in the reference-list just show up as (?). What is my mistake?
I do
latex test.tex
latex test.tex
bibtex bu1
bibtex bu1 ...

dear Stefan, great to have your professional advice. Below is the realization. It works! Thanks
Of course, a dream remains to have the two .tex files as input, and teach latex to pick the stream of characters from the left.tex file for the left pages and from the right.tex file for the right side ...

I have the task to have two separate texts, say "L.tex", "R.tex" to be combined in one book, with "L.tex" always on the left page, and "R.tex" always on a right page. Each is to have its own \newpage. Someone out there to know a solution?