Institute for Biostatistics and Medical Informatics, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, SI-1104, Ljubljana, Slovenia. dimitar.hristovski@mf.uni-lj.si.|Faculty of Medicine, University of Maribor, Slomškov trg 15, SI-2000, Maribor, Slovenia. dejan.dinevski@um.si.|Faculty of Information Studies, Ulica talcev 3, SI-8000, Novo mesto, Slovenia. andrej.kastrin@guest.arnes.si.|Lister Hill National Center for Biomedical Communications, U.S. National Library of Medicine, 8600 Rockville Pike, Bethesda, MD, 20894, USA. trindflesch@mail.nih.gov.