Elling, VolkerVolkerEllingLiu, Tai-PingTai-PingLiu2010-10-152018-06-282010-10-152018-06-282005-01http://ntur.lib.ntu.edu.tw//handle/246246/216239en-USThe ellipticity principle for self-similar potential flows.journal article10.1142/S0219891605000646