also generate DOI in 856u, see ubtue/DatenProbleme#68
also generate DOI in 856u, see ubtue/DatenProbleme#68

ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools,ubtue/ub_tools