Multivariable backward-shift-invariant subspaces and observability operators. - Joseph A. Ball; Vladimir Bolotnikov; Quanlei Fang (Multidimens. Syst. Signal Process., 2007)

Equivalence of robust stabilization and robust performance via feedback. - Joseph A. Ball; Quanlei Fang; Gilbert J. Groenewald; Sanne ter Horst (Math. Control. Signals Syst., 2009)