Leonid M. Fridman Arie Levant Jorge Dávila 0001 High-Order Sliding-Mode Observation and Identification for Linear Systems with Unknown Inputs. 5567-5572 2006 CDC https://doi.org/10.1109/CDC.2006.377385 conf/cdc/2006 db/conf/cdc/cdc2006.html#FridmanLD06