@unpublished{TUW-295801, author = {Nothnagel, Axel and Krasna, Hana}, title = {Reference epochs in VLBI estimations of clock parameters}, year = {2021}, note = {poster presentation: 25th Meeting of the European VLBI Group for Geodesy and Astrometry, Cyberspace; 2021-03-14 -- 2021-03-18} }