fixing the pack option

Makefile

@@ -164,7 +164,9 @@ pack: $(TEXSRC)
                  if grep --quiet $(shell basename $(THISDIR))/$$(basename $$file) *.log; \
                     then cp -v $$file submission; \
                  fi; done
-	cp *.bib *.bbl *.bst submission
+	cp *.bib submission || echo "There are no bib-file!"
+	cp *.bbl submission || echo "There are no bbl-file!"
+	cp *.bst submission || echo "There are no bst-file!"
 	# copying all files from the current directory mentioned in log-file
 	for file in *; do if grep --quiet $$file *.log; then cp $$file submission; fi; done
 	# remove comments