People v. Wills , 61 Ill. 2d 105 ( 1975 )
Boykin v. Alabama , 89 S. Ct. 1709 ( 1969 )
People v. Davis , 145 Ill. 2d 240 ( 1991 )
People v. Delvillar , 235 Ill. 2d 507 ( 2009 )
People v. Pullen , 192 Ill. 2d 36 ( 2000 )