Volume 16, Issue 1 Qinglan Bao Guangsheng Wei Anton Zettl The Friedrichs extension of regular symmetric differential operators Downloads Abstract PDF Full article PDF DOI { copied = true; setTimeout(() => copied = false, 2000) })" :aria-label="copied ? 'DOI copied' : 'Copy DOI'" :title="copied ? 'Copied' : 'Copy DOI'" > Find all available articles from these authors Qinglan Bao Guangsheng Wei Anton Zettl Find more articles with the same keywords Friedrichs extension symmetric differential expressions boundary matrix Find more articles with the same subject classes 34B24 34L15 34B08 34L05