Peng Cheng Yong-Yan Cao Youxian Sun Strong gamma<sub>k</sub>-gamma cl H<sub>infinity</sub> stabilization with a new slack variable approach. 1861-1867 2009 45 Automatica 8 http://dx.doi.org/10.1016/j.automatica.2009.03.024 db/journals/automatica/automatica45.html#ChengCS09