OBSERVERS IN CONTROL SYSTEMS http://hdl.handle.net/123456789/4135 Mon, 06 Apr 2026 01:58:48 GMT 2026-04-06T01:58:48Z OBSERVERS IN CONTROL SYSTEMS http://hdl.handle.net/123456789/4146 OBSERVERS IN CONTROL SYSTEMS GEORGE ELLIS Tue, 01 Jan 2002 00:00:00 GMT http://hdl.handle.net/123456789/4146 2002-01-01T00:00:00Z